I want my son to use my last name not his father his father is not in his life and I don't get any help from him on the birth cert he has his father and mine last but I was using his father I can't change it in the school what should I do he dose not know his father I don't know where he his.

You have to go to court for a legal name change. You will probably have to get the father's permission or at least show you tried to.