ipod won't sync

i don't know what to do, yesterday my iPod had a Red x on it, i managed to fix that, but now it won't sync at all, saying it failed to copy to disk and saying that ipod cannot be found when it shows up on the side bar, i've tried almost every trick in the book, literally, nothing seems to work and i'm really starting to lose patience for this thing, it was fine ever since now, i just want to make it work again, movies sync fine but my music won't sync or it'll stop half way saying cannot find ipod or disk, or it'll say i have to restore it because it is corrupt, i've tried dfu mode but that doesn't work either, could someone give me more diagnostic tricks i could try? please and thanks 🙂