My iphone 4s won't sync my music from my phone?

They are both updated to the newest software but for some reason it won't sync, I'm thinking it might have something to do with the fact that I was in a rush to get out of class the other day and so I quickly cancelled the sync whilst it was syncing and unplugged my phone… Can anyone help!

Added (1). I have downloaded new music on itunes on my mac and I want to put it on my iphone but its not transferring. It says it is but then when the sync is complete there's no music

What are you trying to say? You can't transfer music files on a iphone to any other device without first getting the music on your computer.