Well derailleur hangers are bike specific, you probably can't use one from a different bike. The hanger itself is the piece that bolts onto the frame that has the hole that the derailleur mounts to. Usually when you crash you'll bend that hanger, so if the cage looks bent that may be why. You'll need to determine if it is the hanger or the derailleur itself, you would have had to hit the cage really hard to bend that before you just bent the hanger.
P.S. we want details on your crash!! :wave: