I moved all of my music off the computer onto my external hard drive yesterday, and unfortunately somehow lost about 8GB in the process...that's not recoverable (I don't think??? please correct me if I'm wrong!), but today, iTunes won't let me listen to anything at all. The music library is set to the right location, everything's plugged in and turned on properly, but when I press play, it freezes and the colour wheel spins for ages. Does anyone know how to fix this? Also, the play/rewind/fast forward shortcuts on my keyboard aren't working either. I'm seriously unimpressed.

Please please please help!