Windows ME

Whenever I try to delete a file, I receive a message "Cannot delete ___. Access is denied. The source file may be in use."

This happens no matter what file I try to delete. What could be using every file on the C drive? How do I regain access to these files? I have restarted the computer several times without success.

For several years, I have deleted files daily, and they always went to the recycle bin, as expected. Now, the recycle bin also is empty, though I know there were some files in the recycle bin.

RichardP, sounds pretty nefarious to me. I suspect that there's a nasty at work here.
Meanwhile, back at the ranch, go into safe mode and see if you can delete from there. That loads a minimum of things and often, we can do things that are otherwise blocked.
If that fails, deleting from DOS ought to be allowed.
HTH.
Ed in Texas.

Try Move On Boot
That should work for you...Good Luck

Hopefully my advice will help you...Please post back with your results....thanks