Crashes happen. And even more often, bikes sometimes just fall over. Knocking your rear derailleur hanger out of alignment is a common side effect of snafus like these. Sometimes you can bend it back, sometimes you can't. The alignment of your rear derailleur is critical in ensuring precise shifting, so when realignment isn't an option, it's time to replace the hanger.
This replacement derailleur hanger is identical to what we use on new ALLIED frames. Select the version that matches your frame model, and whether you use a standard mount or direct mount.