Macbook Pro can't can't connect to server

Question

Disclaimer: I have been trying to solve this issue for days. I've tried taking different steps to solve this issue, however I am not the most computer savvy. I'm having multiple issues that I believe are all related to the same unknown problem. Please bear with the length:
I tried connecting to iTunes and I get an error message:
"The certificate for this server is invalid. You might be connecting to a server pretending to be 'init.itunes.apple.com', which could put your confidential information at risk. Would you like to connect to the server anyway?"
If I click "cancel" I get an -9807 error message popup. If I click "continue" instead of "cancel" I keep getting the above message but with different server names such as p14-buy.itunes.apple.com, but I have not clicked "continue" all the way through the pop up warning messages. I'm afraid to do so honestly. I don't want to connect to a bad server or something (if that is even possible).
If I try to reinstall iTunes from the apple.com I get this message:
"'Install iTunes' is damaged and can't be opened. You should eject the disk image"
My computer will not load the app store so I can't do any updates. It will open but the store content will not load and I just get a blank gray box with the App store tabs such as "Featured" etc.
I went onto Find My iPhone on iCloud.com and it says my Macbook has been locked since Nov. 10, 2014. I can't remember anything specifically going wrong on that day. I tried accessing iCloud from System Preferences. When I typed in my iCloud password, it would not let me access the iCloud options so I signed out. I tried signing back in immediately after and I got a message saying that I cannot sign in at this time. I continue to receive this message.
I was getting a server error message for Calendar whenever I opened it until I logged out of iCloud.
iCloud on my iPad Mini and iPhone 6 is just fine.
I've ran a permissions repair just to see if it would fix anything and it didn't. I've tried accessing System Roots from Keychain Access, as directed by a YouTube video, but it is in Read Only mode so I can't do anything with it, and there is nothing listed in System Roots as far as I can see anyway.
What seems to be the overall issue and how can I solve it?

Answer 1

This could be a complicated problem to solve, as there are several possible causes for it.
Back up all data, then take each of the following steps that you haven't already taken. Stop when the problem is resolved.
Step 1
From the menu bar, select
           ▹ System Preferences... ▹ Date & Time
Select the Time Zone tab in the preference pane that opens and check that the time zone matches your location. Then select the Date & Time tab. Check that the data and time shown (including the year) are correct, and correct them if not.
Check the box marked 
          Set date and time automatically
if it's not already checked, and select one of the Apple time servers from the menu next to it.
Step 2
Triple-click anywhere in the line below on this page to select it:
/System/Library/Keychains/SystemCACertificates.keychain
Right-click or control-click the highlighted line and select
          Services ▹ Show Info
from the contextual menu.* An Info dialog should open. The dialog should show "You can only read" in the Sharing & Permissions section.
Repeat with this line:
/System/Library/Keychains/SystemRootCertificates.keychain
If instead of the Info dialog, you get a message that either file can't be found, reinstall OS X.
*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. Open a TextEdit window and paste into it by pressing command-V. Select the line you just pasted and continue as above.
Step 3
Launch the Keychain Access application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Keychain Access in the icon grid.
In the upper left corner of the window, you should see a list headed Keychains. If not, click the button in the lower left corner that looks like a triangle inside a square.
In the Keychains list, there should be items named System and System Roots. If not, select
          File ▹ Add Keychain
from the menu bar and add the following items:
/Library/Keychains/System.keychain
/System/Library/Keychains/SystemRootCertificates.keychain
Open the View menu in the menu bar. If one of the items in the menu is
          Show Expired Certificates
select it. Otherwise it will show
          Hide Expired Certificates
which is what you want.
From the Category list in the lower left corner of the window, select Certificates. Look carefully at the list of certificates in the right side of the window. If any of them has a blue-and-white plus sign or a red "X" in the icon, double-click it. An inspection window will open. Click the disclosure triangle labeled Trust to disclose the trust settings for the certificate. From the menu labeled
          Secure Sockets Layer (SSL)
select
          no value specified
Close the inspection window. You'll be prompted for your administrator password to update the settings.
Now open the same inspection window again, and select
          When using this certificate: Use System Defaults
Save the change in the same way as before.
Revert all the certificates with non-default trust settings. Never again change any of those settings.
Step 4
Select My Certificates from the Category list. From the list of certificates shown, delete any that are marked with a red X as expired or invalid.
Export all remaining certificates, delete them from the keychain, and reimport. For instructions, select
          Help ▹ Keychain Access Help
from the menu bar and search for the term "export" in the help window. Export each certificate as an individual file; don't combine them into one big file.
Step 5
From the menu bar, select
          Keychain Access ▹ Preferences... ▹ Certificates
There are three menus in the window. Change the selection in the top two to Best attempt, and in the bottom one to  CRL.
Step 6
Triple-click anywhere in the line of text below on this page to select it:
/var/db/crls
Copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select
          Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.
A folder named "crls" should open. Move all the files in that folder to the Trash. You’ll be prompted for your administrator login password.
Restart the computer, empty the Trash, and test.
Step 7
Triple-click anywhere in the line below on this page to select it:
open -e /etc/hosts
Copy the selected text to the Clipboard by pressing the key combination command-C.
Launch the built-in Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window by pressing command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting. A TextEdit window should open. At the top of the window, you should see this:
# Host Database
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
127.0.0.1                              localhost
255.255.255.255          broadcasthost
::1                                        localhost
fe80::1%lo0                    localhost
If that's not what you see, post the contents of the window.