Sorry about your chicken. She may be suffering from wry neck, also called torticolis or crook neck. It can be a sign of head or neck injury, vitamin E deficiency, and sometimes seen as an early sign of Mareks disease, fowl cholera, and some others. It is very common. Give her 400 IU of vitamin E daily along with some extra thiamine (B1) which you can find in chick vitamins, B complex, and in some foods. A little cooked egg is good as well for selenium. Make sure that she is able to get enough food and water, and you may need to offer her food made mushy with water and feed her 3 times a day. It varies how long they may suffer from this depending on the cause.