Death of childs mother

I have a child support order, that I pay every month for my son that i have not seen since he was 3 (15 now). His mother died last November and the child now lives with just his step-father.
There was never a custody order filed, so as i understand I now have full custody. Talked to step father and he informed me that if I made contact with my child he would disapper.
The money that I pay every month is just sitting in a CSR account because the have no one to pay that to.
I discusseed that with step father in hope that some financal help for him would help me get some visitation.
He does not want it.
So is there a way I can get this money back? It is getting close to 20k that I could use for my other kids.

Call the office that is collecting it and explain the situation; they should help work out a solution with you or at least help ensure that the money is being used correctly ultimately. Get counsel involved if you have to.