I can't find my

I bought a ringtone from the iTunes Store a few days ago on my iPhone. It worked perfectly fine and it was my ringtone up until yesterday. I don't know what happened but when it changed to the default ringtone, I went to go change it back. But I can't find it anywhere. It's on my iTunes on my computer and it says it synced to my phone but it didn't. I have other ringtones that I downloaded from elsewhere and they downloaded fine. But it makes me mad that I paid money for one from iTunes and it doesn't show up on my phone. Please help me.