Ok first of all do not download anything except recovery software, preferably to a different drive.

Second: I have had great results using a tool called Restoration, but you have to know the filenames or part of them for using it. Link is in this post, as well as links to other recovery software: accidently deleted songs

If that doesn't work then there are links to others here: DELETING FILES FROM LIMEWIRE LIBRARY-DON"T! - File recovery advice!