About 2 weeks ago I booted up LimeWire to download some new music. I did that and then looked at my library to play it, and all my songs, movies, and other files were gone. I did not do anything to them, like delete or anything like that.

I would assume, and hope, that the music files are still on my harddrive, but I am not sure.

Any help is appreciated!

Use your computer's search to look for some of the file names. If the files aren't there, maybe they were deleted by mistake.
You might be able to recover some using a file recovery tool. But since it's been 2 weeks I don't know if that would be very successful. Have a look through the thread below anyway

Deleting files from LW library - Don't!! File recovery advice