If you just rebooted, all your files should still be on your computer.
If you reformatted, that's altogether different.

There is no list of what you have downloaded. If there were such a list, Gnutella would have gone the way of Napster. And if someone else had copied all your dls, you would still have to dl the copy. You may find help here http://www.gnutellaforums.com/downlo...downloads.html