I have no idea how an iPod works, i got the 'old' fashioned MP3 player.
I'll try to give you a few tips tough.
On most of the systems, there is a 'reset' button. Try to reset the system and see if it works again.
Did you drop the iPod lately?
Try to reset the battery.
If this doesn't work, see if you still have a warranty, and return it to the store where you bought it.