Boot up problem - stuck a grey screen

My 2008 macbook pro that won't start up all the way. When i press the power button, the grey screen comes up and freezes there. No apple icon, just the grey screen.
I can zap the PRAM, but it won't respond to any other keys such as safe mode, option key, boot DVD or CD keys.
I used to be able to unfroze by plugging and unplugging a USB device. However this trick no longer works.
Anyone have any suggestions to fix, or maybe know what wrong?

You want to start by removing all USB and firewire devices. If the ports were already going bad, requiring you to remove and reinsert them, then odds are they've degraded to the point where if they are present at all, they will cause problems. It might even be that the damage is so extensive that you'll need a new logic board. But start by just removing any device attached to your system that isn't part of the computer itself.

Similar Messages

G5 start up problem: stuck at grey screen with fans running full strength

hi, i'm new to discussions, so i hope this question and my technical knowledge and descriptions will be OK: problem: G5 20" stuck at grey screen with fans running full strength..
so far i've tried but did not work:
- power off by pressing the button for 5 secs,
- checked all cables connections etc, take out the power cable try again, etc.
- removed all USB connections, re-did
- tried to use it as 'target drive' connected to my macbook by firewire
- tried to start up and keeping C key pressed
- tried to start up with 'shift' key pressed
- tried to start up with command, options, P and R keys pressed,
- i had an additional RAM, i've taken it out and tried again, no luck
- i've put in Mac OS X install disc1, no luck, and now disc is inside my iMac, can't take it out
any recommendations? thank you!

Scroto,
You may not actually have a bad processor. On the Dual G5's it's not uncommon after a few years for dust and corrosion to build up between the processors and their sockets. You can fairly easily remove the processors and clean the connections yourself if you're at all handy. Basically, snap off the heatsink covers, loosen a few screws and the processor and heatsink come out as a unit.
Clean the contacts on the processors (carefully). And clean the sockets. Be sure to put the same processor in the same place or you'll have issues.
I used 90% isopropol alcohol to clean mine last year. Let it air dry and blew both the socket and the cpu off after with canned air. That done, I reinstalled the processors, buckled everything up and no more "bad" processor... The machine worked perfectly from then on and I assume it still does today. Don't know, someone stole it last month:(...

Start up problem - stuck on grey screen

I can't get past the grey screen - I have an apple and a rotating gear but it never advances. I tried disconnecting peripherals, restarting, restarting in safe mode but nothing seems to work. Help!

Last night the electricity went out and my power surge protector was not working so my iMac just force shut downed.
So, when the electricity came back i turned on my Mac but it is *Stuck in the Startup/Boot Screen with a Grey Apple Logo,a Empty Progress Bar with stays for 1 or 2 minutes and a small Spinning Wheel which would Spin Forver! I Have tried the SMC and Pram reset but no use, i have also tried to insert my OS X Lion 10.7 Installation disk and it would not load if i hold the C Key in the Startup, I Have Managed to go to Disk Utility Through "Recovery HD" but the Volume "Macintosh HD" is Greyed out and Unmounted and i cannot repair it. There are some files that i'd like to Recover if there is a way to fix it without deleting files.
**PLEASE HELP ME FIX THIS!**
Details about the iMac:
iMac 21.5 Inch i think from Mid 2010,
OS X Lion installed maybe 10.7.2 or 10.7.3 (im not sure)

Intel-based iMac stuck in grey screen with spinning wheel. SMC::smcReadKeyAction ERROR THOP kSMBadArgumentError(0x89)

Hi guys,
since yesterday my Intel-Based iMac doesn't boot normally, its stuck in grey screen with a spinning wheel.
Its an Intel-based iMac 21.5'' purchased in 2011, and i recently (2 months ago) upgraded it to Mavericks.
-2 weeks ago, i installed smcFanControl app
-Tried start up in Safe Mode by holding Shift but its not working. i think i hear fans are working more than they were before the problem occurs.
-entered Single User Mode and i get an error
SMC ::smcReadKeyAction ERROR THOP kSMCBadArgumentError(0x89) fKeyHashTable=0x0xffffff8029fa1000
-followed some instructions found online, but can execute the correct commands in SingleUserMode
tried to remove FanControl as explained here: http://apple.stackexchange.com/questions/110667/errorr-kernel-smcsmcreadkeyactio n-in-console
any ideas what may caused this and how can i fix this?
Thanks in advance

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
Step 1
The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.
There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.
a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.
b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, boot from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.
c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
If the startup process stops at a blank gray screen with no Apple logo or spinning "daisy wheel," then the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.
Step 3
Sometimes a startup failure can be resolved by resetting the NVRAM.
Step 4
If you use a wireless keyboard, trackpad, or mouse, replace or recharge the batteries. The battery level shown in the Bluetooth menu item may not be accurate.
Step 5
If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.
Step 6
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
Step 7
If you've started from an external storage device, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.
Start up in safe mode. Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a Fusion Drive or a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you start up in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 10. If you ever have another problem with the drive, replace it immediately.
If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)
If the startup process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 8
Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.
Step 9
Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 10
Do as in Step 9, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.
Step 11
This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's and some others (not current models.) Both desktop and portable Macs used to have such a battery. The logic-board battery, if there is one, is separate from the main battery of a portable. A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 12
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

Mac won't boot, stuck on grey screen if the external hdd plugged in

as the title.
if i plug my external drive, via usb port, the mac won't boot and stuck at grey screen.
unplugging it, the boot process will continue.
the hdd is a LaCie mobile hdd
any help?

Hello jason(?)
It's a LaCie external mobiel hdd, formatted as exFAT. without adapter. take power directly from usb port.
i tested it on my iMac and it works fine. boot up as normal. the only difference is my iMac is on 10.6.8 and my Air is on 10.7.2
I tested on both USB port on my Air and the problem still persist.
the read/write speed is normal (bought it like a day ago).
another thing is I don't have this problem with my external WD drive.
One thing to notice is that, I accidentally left like for like 2-3 mins and it boots. So why the question now is why it's taking so long to boot? normally it just takes <20 seconds. Seems like it tried to boot from the external hdd, doesn't it?

My old mac powerbook g4 wont boot up, it wont show apple logo and spinner aswell just stuck on grey screen while booting please help me

i have a old powerbook g4 which i usally use to store some photos and to listen music. the battery of my powerbook is completly dead so i used to use my powerbook using charger adapter so whenever my power cuts down my laptop will be shutdown.
one day i had just bootedup my powerbook and some date notificateion poped up so i press enter and suddenly my power went off and laptop shuted down. and next time when i tried to boot its stuck at grey screen , i even cant reach the apple logo and spinner. please helppp me :!!!!!!!!!!!!!!!

Resetting PRAM and NVRAM is not working
and i cann't boot it on safemode holding shift button and while holding option or c button at startup i can only see three things 1 is refresh button, 2 macintosh HD with X under it, 3 arrow forward button please help me

10.6 won't boot; stuck on grey screen

I know this is covered here to some degree, at least, but I haven't been able to find a complete solution/answer, so here goes:
(Please, redirect me to the right source of information, if you know where to look, but not before reading through my post. Thanks! Oh, and I'm no computer expert, so, please, bear with me.)
First of all, my equipment: 17" iMac (serial #: w86262cru2n, emc #: 2104), running (ran?) 10.6 (w/updates)
So, as my title says, my iMac won't boot up and gets stuck on the grey startup screen with the  and the spinning wheel. I can wait and wait, but it never gets past this point.
Here are some things I've tried (nothing has worked so far; "no success" = stuck on grey screen). These steps are also laid out here.
- Tried normal startup (no success)
- Tried Safe Boot (no success)
- Tried booting without connected peripherals (no success)
- Tried alternate outlet (power source) (no success)
- Tried resetting PRAM & NVRAM (no success)
- Tried boot from 10.6 Install Disk (no success)
- Tried replacing original RAM (no success)
- Tried mounting internal drive as Target Disk on my 10.5 MacBook (mounts fine; used 10.6 install disk to verify, says disk is "ok")
- Tried booting to MacBook via Target Disk (i.e. iMac is external drive connected by FireWire) (no success)
- Tried booting from cloned copy of 10.6 disk on an external USB drive (yes, this can be done; I've done it before). This drive was verified "ok" in the same way the internal disk was (see above). (no success)
My next step appears to be to erase the original internal HD and reinstall 10.6. This is where my my ignorance begins to rear it's head. Since I can seem to boot from the iMac, can I do this through my MacBook, viz. mount the original, internal, 10.6 disk on my MacBook and erase it and install 10.6 from there (e.g. through Disk Utility on the 10.5 MacBook)?
Assuming this is possible, can someone step me through the process?
Assuming this last step isn't possible, does this all point to a faulty logic board (sounds like a 'worst case' to me)?
Any ideas? Suggestions?
Many, many thanks, BTW, to all who have posted here and whose help I've availed myself of anonymously many times. And thanks in advance to anyone with helpful ideas.

Try a SMC reset and follow the steps again in the support doc for grey screen
https://support.apple.com/kb/ht3964
https://support.apple.com/kb/TS2570
Your 10.6 install disk seems unreadable if it won't "hold c or option" boot.
Clean the bottom with a alcohol and a very soft cloth and lightly polish until there is no streaks.
Don't touch the bottom or place the disk onto something that will mar the bottom.
If the disk still fails to work, get a replacement, as your going to need it. Get a jeweled plastic case for it.
To make copies of your Snow Leopard install disk, follow these directions.
http://www.walterjessen.com/make-a-bootable-backup-snow-leopard-install-disc/
Once you can hold c and boot off a working 10.6 install disk, simply reinstall OS X without using Disk Utility to Erase and Format the drive, this will replace the OS X installed (and bundled programs) with the disk versions, then reboot and immediately use Software Update to get current.
Your user files, third party programs will remain untouched, except for ones installed in OS X/root system files, those will have to be reinstalled with updated copies.
All else fails:
Grab a copy of your recent user file folders via FireWire target disk mode first or from a hold option bootable clone on a external drive
If you have to completely erase and reformat the drive, reinstall 10.6, there are some things you need to know.
1: The free iLife that came with your 10.5 install disks are not on the 10.6 retail disks
So to get that you need to select the drive makers name in Disk Utility, erase and install with the 10.5 disks first (warning, wipe entire drive)
2: Name the boot drive the same name as before in Disk Utility when formatting.
3: When you go through inital "Welcome to Mac" setup, use the same username as before, (different password)
4: Once in OS X 10.5 stick a working 10.6 installer disk in and upgrade. Once rebooted, immediately Software Update to current version.
5: Install programs from fresh sources next and update.
6: Finally, return the backup copies of your user file folders (Music, Documents, Pictures, etc., not Library) to their respective folders on the new configuration. Because you used the same hard drive and user name as before you should have little complications with things like iTunes song locations/playlists and other hard references to files on your drive.
By installing the OS first, then upgrading, then programs, then finally user files last, keeps the drive optimized as the drive is faster on the data installed first than data installed later. Since users files change size often, having them towards the end where they can grow or shrink keeps the performance of the computer up as much as possible for the OS and applicaitons. Eventually though with OS X updates it can get a bit more defragmented, but not much.

Macbook pro model A1278 wont boot osx stuck at grey screen

I have had my mbp for about 3 years now and has worked great. Just today i got home from work and when i opened the macbook which was already running I was in OSX but it was frozen with colored wheel spinning. I had never experiened this before but I didnt think too much of it and held down the power button to reset it. Now i am stuck at the grey screen with the Apple Logo and spinning wheel and cant get back into OSX at all. So i started googling (on another computer obviously) and tried:
1. boot in safe mode. Didnt work, still stuck at grey screen
2. boot in safe mode with "commd-shift-v" to see info. stuck in "dos" looking screen. see pic at bottom.
3. tried resetting VRAM w/ "commd-opt-p-r". did not work, still stuck at grey screen.
4. got original OSX install DVD. Was able to boot to disc and make it to disk utilities. went to repair and got error "unable to unmount disk"
5. ran "repair permissions" and completed that. ran "verify disk" and got green "disk ok" message. then re-ran repair and got same "unable to unmount disk"
so know i am worried. my main concern is the 80 GB of music I have on this computer (and dont currently have backed-up {que back-up lectures}) and my pictures. Does it sound possible to recover music and pics based on this little bit of info? Im willing to take it to the Apple store and pay the price if it sounds like I can recover it. I am pretty computer savy but am reluctanct to just start trying anything that could lose my music/pics. I cant try just deleteing and restoring OSX to factory settings and losing all that music/pics.
so...what is best approach to access and back up these files myself? I do have another macbook with a firewire connection but am not familiar with that process. I will get a external HD immediatly (now ofcourse)...can I backup my files from disc utility?
Thanks for any help.

Sorry about specs...i entered in drop box menu but realize doesnt show on thread:
MacBook Pro "Core 2 Duo" 2.53 13" (SD/FW)
2.53 GHz Core 2 Duo (P8700)
Intro Date:
June 8, 2009
Disc Date:
April 13, 2010
Order No:
MB991LL/A
Model No:
A1278 (EMC 2326*)
Subfamily:
Mid-2009 13"
Model ID:
MacBookPro5,5
Std RAM:
4 GB
Std VRAM:
256 MB
Std Storage:
250 GB (5400 RPM)
Std Optical:
8X DL "SuperDrive"
I was running the last vesion of snow leopard (10.6.8 i think).
I picked up a firewire today and am going to attempt to make "broken" macbook target and pull files onto other macbook. Will give an update tomorrow after attempt. Thank you for fast response.

Mac Pro Stuck at Grey Screen, then will only boot into OS X Utilities.

My Mac Pro is stuck at Gray Screen. When I reset PRAM, it loads the OSX Utilities screen, prompting me Restore from Time Machine, Reinstall OS X, Get Help, or Disk Utility. I ran Disk Repair and Repair Premissions, same thing.... stuck at grey screen.
What will happen to the data on my HD if I choose to Reinstall the OS X? IS that the best choice? Thanks.

Off hand I think your drive may be bad. But to find out you need to erase the drive, so you will need to have a recent, bootable backup.
Install or Reinstall Lion/Mountain Lion from Scratch
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your startup volume (usually Macintosh HD) from the
      left side list. Click on the Erase tab in the DU main window.
3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
        the Security button and set the Zero Data option to one-pass. Click on
      the Erase button and wait until the process has completed.
4. Quit DU and return to the main menu.
Reinstall Lion/Mountain Lion: Select Reinstall Lion/Mountain Lion and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
            because it is three times faster than wireless.
If this does not work, then you need to replace your hard drive.

Macbook does not boot. stuck at grey screen. have tried single user mode, but text stops at AppleIntelCPUPPowerManagement: initialization complete, without anymore prompts. no

macbook does not boot. stuck at grey screen. have tried single user mode, but text stops at AppleIntelCPUPPowerManagement: initialization complete, without anymore prompts. no hash key appears that will allow me to type in: fsck -fy
have my trials for IB in one week and my history notes are all on my hard drive, that has not been backed up. help please =(

macbook does not boot. stuck at grey screen. have tried single user mode, but text stops at AppleIntelCPUPPowerManagement: initialization complete, without anymore prompts. no hash key appears that will allow me to type in: fsck -fy
have my trials for IB in one week and my history notes are all on my hard drive, that has not been backed up. help please =(

After boot back from windows to OS X it stuck at grey screen

After using windows 7 and use bootcamp to get back to OS X
it stuck at grey screen with apple logo and the circle
i'm be able to boot using option for choosing windows anytime now,
but i can't use OS X and everytime booting back to OS X it stuck at greyscreen
can anybody help me with that
i'm using windows7 on mac OS X v10.7.5 lion to type this
i have tried repair the disk using disk utilities from recoveryHD but it didn't work at all
so if anybody knows how to solve pls tell me
i did't backup anything on OS X and i feel sorry for that now
The HDD work find though i can still get files from OS X partition.
so if i have to backup i think i should be able to backup through windows 7
PLS HELP!!!!!!!

Reinstalling Lion/Mountain Lion Without Erasing the Drive
Boot to the Recovery HD: Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the main menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu.
Reinstall Lion/Mountain Lion: Select Reinstall Lion/Mountain Lion and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

Powermac G5 stuck on grey screen start up and fans running wild

Hi All
I also have the recurring problem all of a sudden - yesterday all seems well, today am stuck on grey screen and fans getting stronger by the minute. NOTHING works - have been through all sorts of forums and the most I got was to try disk utility - which says all is well - replaced the battery - tried just about anything short of pouring some acid on the **** thing, won't boot from original install CD either - I really need this machine as I earn my living with it and cant afford a new one and why as it was working just perfect - now this mess. In a way don't know why the excellerating fans are not built to simply pick up speed and then eat into the PC board and CPU - at lest this way we know for sure there is nothing we can do.
Does no one here know why the mac is doing this - not even the mac fundies? Unbelievable. I live in Namibia and Apple Mac support here is similar to that on this website - might as well write this on a wall - that is why I am really frustrated... **** Mac

Follow these steps in order:
http://support.apple.com/kb/TS2570
The G5 is also subject to solder failure around the RAM slots and memory controller.
It is a fatal condition, but one that can sometimes be temporarily sidestepped by heating the logic board between the RAM slots with a hair dryer.
Heat the board until very warm (hot) then start.
If your machine starts after heating, then you better just leave the machine on all the time.
You never know when the trick won't work......

STUCK ON GREY SCREEN! !PLEASE HELP!

!!HELP!! STUCK ON GREY SCREEN
I have a MacBook 10.5. Its a few years old anyway it seemed to be working fine up until a couple of weeks ago then it started taking ages to startup.
I started it in singlemode then typed /sbin/fsck -fy then a message came up "harddrive appears to be ok" next i typed "reboot" and the system started booting.It started as normal with the apple logo and spinning chime,next the screen turns blue where the login screen normally appears but then the screen turns grey with no logo with just the pointer arrow on it and it doesn't seem to load past that point.Can anybody please help me solve this problem i have my kids photos and stuff on it that are unreplaceable.
Hopefully there's a command line that can help also I don't have a installation disk so is there a way I can download 1 onto USB??
THANKS HEAPS!!!!!

Hi Eug07349,
Thanks for visiting Apple Support Communities.
It sounds like you may be experiencing a software issue. I'd suggest trying the first two steps in this article (Disconnect, test peripheral devices and network cables, Perform a Safe Boot):
Mac OS X: Gray screen appears during startup
http://support.apple.com/kb/ts2570
Best,
Jeremy

My macbook pro is stuck on grey screen with apple symbol in center with the progress circle under it continusly spinning. After I had turned it on. Prior to turning it on I had to force close and shut down a few hours prior. Please Help?

My macbook pro is stuck on grey screen with apple symbol in center with the progress circle under it continusly spinning. After I had turned it on. Prior to turning it on I had to force close and shut down a few hours prior. Please Help I have tried everything I know to do

Unfortunately this means that there is a problem in the boot sector of your hard drive. It might be indicative of a fundamental corruption in the coding that allows your computer to boot your operating system from your hard drive. I had this problem twice and it resulted in me having to get a new hard drive and restore my data.
In other words, your computer can't talk to your operating system so you can't access your data.
Here is my advice: DON'T CALL APPLE TECH SUPPORT though they are kind and usually helpful it will take you an hour just to explain the situation and they will only tell you to do what I'm gonna say here.
First: Shut down your computer completely
Two: boot up while holding down the following keys: command, option, p, and r. The computer will reboot 3 times. This solution will likely fail so if you're frustrated skip to the next step.
Three: Boot up while holding down the option key. Select recovery drive. Select your default language. Select disk utility, click on Macintosh HD, and select "verify and repair volume." Likely the verification will produce some line like "unused node not erased." Or something like that. If anything using the words "node structure" comes up, you need a new hard drive.
If after verification and repairs you still can't boot I sincerely hope you have apple care because you will need a new hard drive. Set up an appointment to come in to the apple store, they will tell you to go and get data recovery, just ask them to give you the old hard drive. Unless you have an up to date backup in which case you can just restore from that. If you're lucky the only issue is with the boot sector which means that if you ask them to give you the old hard drive, you can buy an enclosure and you have effectively been given a free external hard drive. It still works to store data just not to load an operating system.
If you have a back up drive bring it to the apple store and they'll do the whole thing right there, it should take around an hour and a half but may take longer.
Hope this helps, it's annoying but it's your safest bet.
All the best.

Macbook pro retina 2012 mid year stuck on grey screen

Hi everyone.
I've just update for the lastest mac os x mountain lion update, when half way the progress and it goes stucked. All the function are unable to function, so i've force shut it down. After mac shutted down and i tried to boots it back it stuck on grey screen which below apple logo forever loading icon. i've tried Reset the PRAM, but it still not working for me. Also, i tried when when start up hold with cmd + r to reinstall the os x , but it just won't let me to reinstall it , it wrote you can't upgrade this version of OS X because a newer version is installed?
Help please! need a solution that wont delete all my files at the same time

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
Step 1
The first step in dealing with a boot failure is to secure your data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since your last backup, you can skip this step.
There are several ways to back up a Mac that is unable to boot. You need an external hard drive to hold the backup data.
a. Boot into the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.”
b. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, boot the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
c. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to boot, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can boot now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
If you've booted from an external storage device, make sure that your internal boot volume is selected in the Startup Disk pane of System Preferences.
Step 3
Boot in safe mode. Note: If FileVault is enabled on some models, or if a firmware password is set, or if the boot volume is a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to boot and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you boot in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, your boot volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 5.
If you can boot and log in now, empty the Trash, and then open the Finder Info window on your boot volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then reboot as usual (i.e., not in safe mode.)
If the boot process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 4
Sometimes a boot failure can be resolved by resetting the NVRAM.
Step 5
Launch Disk Utility in Recovery mode (see Step 1.) Select your startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then reboot as usual.
Step 6
Reinstall the OS. If your Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 7
Repeat Step 6, but this time erase the boot volume in Disk Utility before installing. The system should automatically reboot into the Setup Assistant. Follow the prompts to transfer your data from a Time Machine or other backup.
Step 8
This step applies only to older Macs (not current models) that have a logic-board ("PRAM") battery. Both desktop and portable Macs used to have such a battery. The logic-board battery is separate from the main battery of a portable. A dead logic-board battery can cause a gray screen at boot. Typically the boot failure will be preceded by loss of the startup disk and system clock settings. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 9
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store to have the machine tested. If you can't get to an Apple Store, go to another authorized service provider.

Boot up problem - stuck a grey screen

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