Music Won't Transfer To My Iphone?

I've been trying to transfer songs i have bought off itunes to my iphone but nothing will work. I wanted to put them on because i had previously had them on my iphone but they for some reason stopped working on my iphone. I would press play and it wouldnt do anything, and when i pressed play again my iphone would freeze up in the music part and i would have to press the home button and relaunch the music. The songs work fine on my computer. I've tried syncing my iphone and also tryed draging the song/album over to the phone icon to transfer but it won't do anything. Is their a way to fix this? Or should i take it to the apple store to have it looked at?

Since you purchased on iTunes, you can add them directly to the phone without iTunes or computer.

First, did you set up the new phone with your iTunes account and password?
Go to the iTunes Store on your phone.
Click on "purchased"
Click on the cloud icon to download songs