Can I gain legal status thru my legitimate father that I haven't met since I was 2?

I really need some advice and I was wondering if I could gain legal status through the help of my biological father (a U.S Citizen) that I just met. I'm currently twenty years old and I just found out that my father is still around. My mother and father both split up when I was 2, and I think out of frustration my mom refused to have him registered in my birth certificate. So I was wondering how would I go about proving that he's my bio father, hoping that it would help my status, how long would the process take? He's really determined to try to make it up for me for the years that he hasn't been there. I'm going to get legal advice from an immigration attorney. But I just wanted to know what to expect and the possibilities of my situation.