What action should be taken if insurance co. rejects claim for broken leg?

The apartment I live in had the rugs washed, and they were buckled and slippery. Going down the stairs, my foot slipped (I didn’t fall, though) and weirdly twisted, ending up with my upper leg breaking the lower leg. It took me three weeks to get to a doctor, who figured out the fracture. Because I didn’t complain right away, and because there was no witness, the building’s insurance co. rejected the claim (I asked just for my co-pay). Do I have any recourse? Can I take this to small claims court? Do I just forget it? I know I do not want to hire a lawyer. Suggestions?