The mother of my daughter won't allow me to see or spend time with her, what can I do to have my rights back as a father?

My ex girlfriend and I are split up not married but together for four years plus and we had bad argument she assaulted me and I called police on her and we almost had kids taken away to the state if I would pressed charges so I didn't, now that I ask if I can see my daughter or spend time with her I'm denied. I feel that if I would have pressed charges we both would have lost the kids, now I say kids cause she has another child with another man so both kids would have gone to state. Where do I start so I can have the right to bond and interact with my daughter. Thanks for your advice.