I know some viruses also make your hard drive look empty, even when it's not. Maybe try this, or if doesn't help, google some alternative methods for checking for such malware:

http://www.computing.net/answers/security/cant-see-anything-on-c-drive/35355.html

http://www.tomshardware.com/forum/270482-32-hard-drive-empty

Seriously, I wouldn't give up after a big fight. Just make sure any new programs you download/install are on a different drive than the one you are trying to recover. Don't put anything new on the empty drive.