It sounds like your Windows user profile is corrupted. It could have happend when you turned your computer off after the monitor went bad, or if you bumped it the wrong way while replacing the monitor with the computer running.
The corrupted profile is probably not coming back, but you should be able to find it (and hopefully most of your files) under the C:\Documents and Settings\ folder. Make a new user account and copy everything you can from the old one. You will need to redo settings of most programs manually, but there is a very good chance all your files will be intact.
If you receive an "access denied" error while browsing the old profile, you may have to take ownership of those folders as described
here.
