IPod Touch iTunes Problem?

I have an iPod touch that I usually don't bother syncing to my computer, so I rebooted my computer and try to sync my iPod, it wants to replace the music on my iPod with the music on my PC, which is like Beethoven or some other Default Music, is there any way (I have done manually manage my iPod) that I can put the things from my iPod Touch on to my iTunes without having to wipe my iPod? I would not like to pay for any software if it is not necessary.