iTouch not syncing songs???

I got my iPod touch last Christmas and i do not/did not plug it into the computer much. One day i decided i should plug it in at least to back it up, and when i plugged it in and it starteed syncing, 2 seconds later it said, "attempt to copy to disk failed. You do not have enough access privilages for this operation." HELP it is not syncing any of my songs and i only have my purchased songs and it took off all of my songs from my library on the computer from my ipod.

basically

-my ipod only kept songs that i purchased on my ipod

-dang error message keeps coming up

-itouch wont sync!!!!!

help me i beg of you!!!!!😟