I put iOS 5 on my wife's iP4 last night and now she can't play her music. It shows up on the phone and says that it is playing, but no sound. Has anybody else ran across this? Any fix? Thanks ahead of time.
I would look at those particular tracks then, see if an error message comes up, or that maybe the meta-data is messed up. Only other thing I can think of is to make sure that those songs are actually in your iTunes folder. If iTunes isn't set to automatically add tracks to library and you move them, they could be unable to sync.