I updated my iphone . now I do not have my ipod for my music How can I back my music to my iphone

Sync it from itunes on a pc/mac

Or if it was purchased music from the itunes store go to:

itunes store>more>purchased>music

this will show you the music you have purchased from the itunes store with the current apple id that is signed in on the phone.

hope this helps🙂