You have removed your files from sharing ... I hope... You must find where they are on your computer, hopefully if you find one you will find them all, go to tools>options>sharing>shared folders>add share and re-add them. You can also add them through the Library, but the first way is the one I prefer.
You may need this
http://www.gnutellaforums.com/showthread.php?t=49851 ..I hope not But ... I'm not sure what you may have done with your system restore which was not probably necessary...