What I suggest is that you use Ubuntu, to first back up your stuff, just in case.
You can then with Ubuntu access anything that you want.
You may want to try a factory restoration. Each computer is different, but it is usually hitting an Fkey quickly and multiple times during boot. You will lose your stuff but the computer should be like the day that you took it home.
If you cannnot find the method for a factory restoration, give us the make and model of your computer and maybe we can help Use Ubuntu Live CD to Backup Files from Your Dead Windows Computer - How-To Geek
With ubuntu, you can also try to reach last known good configuration. You may want to try in safe mode, also. http://windows.microsoft.com/en-US/w...-Configuration