Pictures or a video of the hen would be good. How long has she been acting like this? What feed is she on? Is she drinking? More info regarding the hen in particular, your setup, etc, would be helpful.
Wry neck is a symptom, not a disease itself, it can be caused by a wide variety of issues such as nutritional deficiencies, neurological damage, viral or bacterial infections, toxicosis, or metabolic diseases. Out of all of those nutritional deficiencies, and neurological damage is experienced most often, so I would try to treat for at least one of those first.
While Poultry Nutri-dench and poultry cell are high in vitamins, they just don't have the amount of vitamin E in them as much as we'd like. If I were you, I would go pick up some human 400iu vitamin E capsules, and give her one a day, orally or over treats. Either prick the capsule with a needle, or cut the top off with scissors and squirt it into her mouth.
https://www.backyardchickens.com/ar...dications-to-all-poultry-and-waterfowl.73335/
Another vitamin the can cause neurological problems, is thiamine (B1), so you may consider either getting some B complex capsules, dissolving them in water, and giving her some orally, or using Cattle Vitamin B Complex, and giving her a few drops orally as well. Offering her mashed scrambled eggs would be good too, as it's high in vitamins, one being selenium which will help absorb the E better. Keep a close eye on her, and ensure she's getting enough feed and water. You may need to support her neck, and move feed/water in front of her face if she can not. If her neck is limp, and not able to support it on her own, I would suggest providing a very shallow water dish, so she doesn't accidentally aspirate.
https://www.fresheggsdaily.blog/2014/04/preventing-and-treating-wry-neck-in.html