What can I do to get the custody of my daugter back?

I was 7 months pregnant and was finally living on my own and I was a high risk diabetic. I kept my middle child with me and my daughter stayed with my mom since that's where she was used to. She was molested by her father at 3 and the move would be traumatic. In case anything happened to me my mom thought it was best to sign guardianship to her. She talked me into it and we met with her lawyer and signed the papers all the while him promising I can get her back after I had my baby and was stable again. 2 months after I signed it I got a call from my mom asking if I was coming to court I never got any papers notifying me of court and because I was not there they granted permanent custody to my mom. I feel cheated and taken advantage of and am not sure what to do at this point. I have a good job with a network company for over two years, have my own car and my own apartment and my other two children. My mom won't let me even see my daughter or spend time with her. Get lawyer gave her the say so of who she is and is not allowed to see. When I ask to spend some time she leaves town with her and it makes me ill. What can I do? I want my daughter back!!