iTunes and iPhone won't sync. PLEASE HELP

Hello. So I have this problem. I have the iPhone 5 and it is fully upgraded in all ways. I used to have a MacBook Pro, also all updated with the new iTunes too, where all my music was syncronized. It broke, and I got a new one. We tried to export all of the stuff from the harddrive, but only documents and some photos was able to be saved. So I lost all of my music. I still had it on my phone though, so I wanted to syncronize my phone and iTunes, which should work but it wouldn't. It does safety copy, but none of the music is exported into my actual iTunes. And now when I download new music on my iTunes on my mac it won't syncronize either. I have tried DiskAid, but it only works one way and I have not bought it yet. This really ennoys me, and I hope someone knows how to help me 🙂