Ipod Touch "The required disk was not found" HELP PLEASE?

When i first got my ipod touch about 3 months ago i wasnt experiencing any problems with syncing songs onto my ipod. But now, every time i try to it either says "the required disk cannot be found" or "this ipod could not be synced because it is not connected" when it's clearly connected. I have tried some of those apple support things but so far none have helped. Also, im a 14 year old so if you could help me, please dont make it too complicated and hard to understand. Thank you!!!