Every time you shut down LW it erases the upload history. If you haven't shut it down(but i assume you did), go to the library page, find the file and look at the "Uploads" column. It looks like this ( 0 / 0 ). The first number is the number of successful uploads the second is the number of attempted uploads.
If anyone uploaded your files there's no way to get them back.
The only other thing you could try is do a search with LW for the files that were compromised. If they show up then you know someone has them. If they don't show up it doesn't really mean anything because the person who has them might not be on the network or they might not be sharing them
.