My iPod Keeps Deleting Songs, help!

My iPod touch (2nd generation) keeps deleting all of my songs. I already checked mark off the 'Manually manage songs/videos/etc' and I even checked mark to stop syncing automatically.... I dont know what is wrong and this is not the first time. It is really getting on my nerves and I'm practically always stuck with an iPod with no music & videos - please help! P.S. All of my apps & bookmark are still on there. It's weird.