How to set up ringtones in your iphone?

So before, i downloaded some music and set it as my ringtone and it was easy, but when i updated my phone to ios 8.1.1 it was suddenly disappeared and i don't know why, i want my music to be my ringtone but now i don't know how to set it up. Can you please help me how to make your music as your ringtone?

Ohh… IOS 8.1.1. That is a terrible update. It makes your phone go crazy. It messes it up and makes it not work right. Sorry. There's nothing you can do. Take it to the apple store.