Child support ; unable to locate father

I’m wondering if anyone has or is going through something like this. I filed for child support back in December, since then, they haven’t been able to locate my children’s father to serve him. I have no idea where he is since we haven’t been in contact since august of 2020. So if they can’t find him to serve him, am I just SOL? Should I possibly look into getting his parental rights revoked? He hasn’t seen them since may of 2020.