It's probably out of warranty, right?
Try
http://www.bootdisk.com for bootable disks and CDs, and make one, and try to access C: (by entering C

from DOS after you boot to it.
If it gives you the C:\> prompt, enter DIR, and see if it gives you a listing of files.
If so, it may be the windows files that are corrupt, so, if you have an OEM copy of a version of windows (preferably linux, hehe), go back to A:, and type format c:.
Press yes (I hope there's no important info on the PC), and wait for it to do its thing. When it's done, you will have a blank hard drive, ready to install an OS.