Well, it sounds like you either need to tube feed her or just put her down. I would understand if you put her down, but I would get a necropsy done. This is just my opinion, but when I have a hen who absolutely will not eat or drink, even my best tempting foods like egg or canned cat food, they have something wrong internally, and I do not tube them. That could be tumors in the crop, gizzard, or intestines, or there is a blockage of the abdominal organs not allowing the digestive tract to work.
I have tube fed, and it is easy to learn, and it only takes a couple of minutes to feed a meal of 30-45 ml of watery feed. You can get some air aquarium tubing from the fish aisle at Walmart, and a large 35 ml syringe from a feed store. The tubing needs to be cut off in a 10-12 inch length, and take a lighter to soften the sharp edges that go into the throat.
This small tubing will work for very watery feed, raw egg, yogurt and medicines to pass through. Ideally a proper feeding tube and catheter tipped syringe can be bought from a vet or online, that will allow feeding of thicker foods. This is a good thread for learning to tube feed:
https://www.backyardchickens.com/threads/updated-go-team-tube-feeding.805728/