Is there anyway to find out who your father is, like a website or something?

Try searching family trees... try Intelius People Search - Public Records, Background Checks & More (http://www.intelius.com)

Were you adopted? Perhaps try the adoption agency, if so.

I wasn't adopted, my mother left my father and I'm not sure she's telling me the truth about who my father is.

Sit her down and tell her how important it is that you find your biological father. And you want any information that she has.

She doesn't know I know and I can't put her through that, she's already in enough pain.