Where do I start

Well I have never met my real dad my mom was 3 months pregnant with me when she met my father the man who raised me as his own he will always be my dad father. But I really want to meet the other man his name is Tony I have looked online called a few numbers all disconnected I have no idea where I go from here my mom doesn't know much about him just his name and he was born in Mexico she bumped into him a few years back and he said hi she didn't talk to him and drove off she has gone by the last address she knew he lived but saw other people there no one she recognized. So i am sitting here thinking what do I do next?