Do you know who injured her? Is she the same age as the others, is she new, or do you have a cockerel or rooster? Spray her head with saline or a pet store wound spray (Microsyn, Vetericyn, etc.) then apply plain Triple Antibiotic Ointment twice a day. Keep her separated inna dog crate with food and water until she is healed. If you could keep the crate in with the others, that might help to get her back into the flock.