When I raised some pheasants last summer I had one of my roosters have almost all of the skin torn off his head wtih the exception of the area just above his eyes. Keep him seperate and kept neosporin on it and he finally got better and grew most all of his feathers back. Including his ring. He is a ring neck. Since I released him I have seen him around the yard a few times this past fall.
Hope your hen gets better.