I just had this same problem with some newly-hatched chicks. They were less than a day old and looked like little owls because their heads were tilted so far back. After searching this forum, I found a few entries that suggested various vitamin concoctions and capsules. In the end I took a left-over prenatal vitamin and dissolved it in a few ounces of warm water. I dipped the chicks' beaks into the vitamin water a few times, put them into the brooder, and hoped for the best. This morning they were acting just like the rest of the chicks, so much so I could not pick them out! I poured a little of the solution into the group watering jar so they would all have access to it throughout the day. This might work for you, too. Since they were at most 18 hours old, I can't say how an older chicken would react to the same treatment. It was (hopefully) an easy fix since I already had a jar of vitamins under the cabinet from when I had my daughter last year. You might be able to do the same with any multivitamin.