Can't access music on iPhone 6

The music on my iPhone 6 was working fine. I originally linked it to my iMac, but I recently plugged it into my Macbook Air to use it as a Hotspot. Since then I have not been able to access my original music that was from the iMac, only my purchased items from my Air. When I plug it back into my iMac I can see all the music and Playlists etc that should be there, but I can't do anything with it. I can't play it, move it etc... Can anyone help?