Can my son's dad change my son's last name from mine to his without me signing anything and with a court order. He was born in Arkansas but the order in =s from Oklahoma.

No, he cannot. If he has done so, notify the court that it was done without your consent and you would like to contest the order.

He has changed it and I never signed any papers. I have already contacted my lawyer about it. He will not give me the because he said he has he just gave me a copy didn't even know it was changed till his first day of school and I'm the one that enrolled him.