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!