Inspect her thoroughly for lice/mites just in case. Put some neosporin on the red areas. That may help her heal quicker especially if there's any cuts or scratches, and keep her away from roosters. When she goes into molt, all her feathers will regrow. In the meantime, I recommend that you buy some gamebird feed which has a higher protein content than regular layer feed. It will encourage feather regrowth. Then slowly wean her off the gamebird feed back to the regular layer feed. Naturally it'll take time for her to regrow feathers, dont expect overnight feather regrowth.