u/Smooth_Plenty2326

Hello, I'm a newbie biker. this is my cousin's bike that has been sat on their garage for like 3-5 years since the owner died, nobody uses it anymore, so I asked if I could borrow it for rides and stuff. I used it the next day and it was all good and nice, but suddenly the chain got stuck while I was riding, then I saw my rear derailleur hanger is what I think is broken, and it won't pedal. Can someone tell me how do I fix this or tell me what the problem is?