What do you mean with "reset"?
For the moment I assume that for some reason you login in the 'default' profile in stead of your own. And that's empty. While your own profile is still sitting on the hard disk waiting for you to get the files safely out. Have a look in Documents and Settings (if XP) or Users (if Vista or Windows 7).
Of course, things might be more serious. But lets not tackle that now.
I turned my computer off normally as usual. Then turned it on normally the next day and everything had reset itself without me doing anything to cause that and i lost all my files. I did not do a back up because i wasnt expecting it to every happen. Is there a way to get my files back?