Tried to recharge iPod nano, all songs gone!

Connected my iPod nano at work to recharge it (as I have dozens of times before), and when I disconnected, there were no songs/artists/albums listed on my iPod! Reconnected to ITunes, and instead of saying "IPOD" it said "New Volume" in the left column, and no songs show either (and the bottom shows only 41 mb of 40gb used, though there is probably 3.5 gb of music on it).

My iTunes is set to manually update and not sync. Is there anyway to recover my songs without a dreaded reformat and reinstall of the 900+ songs on there? Please?