Can't install mountain lion on my macbook pro

Question

Hey everyone,
I have a serious issue since my last senior project my MacBook Pro 15" has been too hard to deal with it hangs a lot and I can't install any updates with out formatting my Mac and have a rough time with it lately I wanted to update my macbook to the latest version which is 10.8.5 and whenever I download that update from the App Store my Mac won't install it then it starts to hang and even hang on the start ups so I formatted it all over again and now when it reaches to the nearly end of the installation like 6 mins left it stuck forever and it writes 2hrs left... I would really be happy if someone can find an end of this drama cause am sick of it

Answer 1

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.