I would like to change my daughters last name to my last name her father is not on the birth certificate but is ordered to pay child support he lives in Ohio and I live in Kentucky do I need his permission to have it changed he had not seen her in 7 months

Yes, A birth certificate is a legal document. Permission from both parents would normally be required for a court to issue a name change order.

A court MIGHT override his objections or lack of response in this situation. I would strongly suggest you consult a local Family Law attorney who can advise of that possibility.

Physical custody and legal custody are two different things. A name change is a legal issue so yes you will still have to have him sign papers for it as well. Have you asked him if he will agree to changing the child's name?