I had a virus and took my laptop to Best Buy for clean up. When I got my laptop back my desktop was empty, but I was told that my files were not lost. How do I uncover hidden files.

Take it back to Best Buy and make them restore them as they lost them in the first place..

Did they reinstall windows? If they did a folder should be on the hard drive that says "windowsold".

It should be in there if they did.