Java Java Data Structures Efficiency! Custom Serialization

Have about 14 "can not get thread main" errors

Hi,

I'm working on this karaoke machine, and all of a sudden, my code stopped working. I have no idea how to post my code, because it's in about 5 files. I deleted some file...stupidly....called SongBook$1.class. The weird thing is, my machine still runs the add, play, and quit options, but when I get to choose, It wont let me choose an artist, it says like 400 cannot read "main" thread or something. As I am writing this, my program now just decided it doesnt want to open at all.......Please Help!! ;( thanks