dishonest manager

In January during my work happend an accident. I cut four fingers. there were a police. I  had administer first aid, I had a operation-sew a part to finger onto a palm.  A manager wrote in the statement i'm guilty,i took out a security myself. When i starts this job manager explain, how machine is functioning, but i didn't have a training in occupational health and safety. During a medical sick leave, manager wrote, that i'm working. How can I against a dishonest manager?