IPOD erased all content and iTunes doesn't have my last back up restore.

My old school iPod that has been my travel music partner all of a sudden last week erased itself has a different interface with none of my music or content!

No songs, no play list nearly full 160gb available. Where is my music and what happened? I have tried to attach to iTunes, no help. Its like its completely different iPod? Do I need to reformat it? How can I load music on it?

Also, iTunes has somehow gotten rid of one of my back ups to restore! What is going on? I am super upset, I have spent so much money in iTunes, and on apple products. I expect to be able to keep all the gens purchases, devices, content I have supported through the years. Is my iPod a paper weight now?

Thank you for all help in advance.