I don't know how, but why not try a reinstall of windows over the current installation - in theory it should not cause any more problems.
Having said that, what is your OS?
If win98 try (from DOS prompt)
[if you have a default installation of Windows]
[this will get you a directory listing of the recycle bin]
[then if the file is there]
xcopy c:\recycled filename.ext c:\windows\system
If you have an understanding of DOS, then adapt the above as necessary. The square brackets are for info only - do not type them. Replace filename.ext with the name of the file and its extension. Where you copy to will depend on where it came from - by default I said c:\windows\system
I am not 100% sure of these commands - it is a while ago since I used them and it is easier to do it in person.