NO CELLULAR DATA OR 4G ON MY IPHONE 4S

I woke up on bay and my 4g symbol was gone! My plan is limited data. I'd if the person paying my bill turn off my data or something is up with at&t in virginia. But I would really like it back can someone help. I thought it could it could be because I almost reach my limit. But can someone help and explain

Well check with that person & AT&T to see what's up.