I am a single mom of 2 kids, my daughters dad only comes to see her when I call and ask him if he wants to have her , my sons dad refuses to see his son and hasn't seen him in 15 months , every time I try to call or contact him about him seeing his son he refuses... Is their anything I can do to get him in trouble for being a absent father? I have no clue what to do.. Please help

You can't force him to be a father. You can force him to provide financial support for his child.