I want my Music!!

I recently updated my iPod 4th generation with the 5.1.1 version update and I can't seem to access my music any more.

At the time I was listening to a playlist A and decided to randomly play a song from another playlist B. The song from playlist B, their picture, name and everything popped up but the music actually didn't play - playlist A was still playing. The screen now goes blank and you can't seem to play anything.

Now it is almost "frozen" and I can't seem to access any of my music. Which is really annoying. - (got most of it from a friend when I was overseas).

I was wondering if anyone else had this problem or if I was a one off.

Answers would be awesome:)

Ninja~