Cannot transfer songs to iPhone 4S (iOS 7)

Was adding a couple songs earlier via iTunes, after transfer I began play back of an album which was previously on my device and !'s appeared next to the files.

I tried to play through my device and every song on my iPhone was now skipping after 1 second as if there was no content/audio.

I have removed all music, readded via Library Sync, Autofill from a Playlist and drag n drop, none will allow me to transfer more than 26 of my 1000 or so songs.

Each generally seems to be the 1st song in each of my albums.

I tried to restore my backup but for some reason it has overwritten itself during the sync's or whatever so thats not possible.

Any one know a fix or ideas?

Thanks