I was dismissed from college over a Lie on the deans

okay I was attending college and i took the day off to go to the doctor for my eyes being that i'm legally blind, i turned in a doctors note that i was given, Because of my vision i asked for it back and they assumed it was a forgery or a lie. They called the doctors to verify if it was a real letter and if i was there that day. I was dismissed because the dean said he was informed that it was a lie and fraud. When i verified with the doctors they said he called in an uproar asking information and stating I was lying and forging documents. I went through the appeals board and they were not trying to listen to me at all and already dismissed me. I want to sue them for one attacking my character on an assumption basically I just want my education. I have a learning disability and to score a 96% on a my midterm is amazing. If i have to sue to get the money to finish it at another school or have them take me back. Please help me.