ipod classic blank after lastest update ???

I have an ipod classic, just updated the latest update from apple. As it was updating it logged me out of itunes, finished update, restarted computer, now my ipod has no music on it although it shows available space left which corresponds with the music I have on it ?? can someone please help I have no idea what I have done and would love to have my music back.

All my music is still on my computer (Windows XP) but nothing on my ipod ???

Any help would be really appreciated