The same thing happened with my hens. I had 9 hens that were about a year and a half old when I got more chicks to add to the flock. My older birds were all laying well, and I was counting the weeks until the pullets began laying as well. But Summer came and went, then fall hit, and ALL the girls stopped laying. I thought it may have been due to their molt. But they all got their beautiful new feathers, and still no eggs. I checked everything you mentioned; stress, light, protein ratio in their feed...getting enough calcium...
Then I realized they had always been free range, but after a loose dog attack, we'd built them a run in late fall. I had always broken up their shells and put them in the compost pile in the yard, and they would eat them when they were rummaging through the compost. They hadn't had any since being confined to the run. So I started sprinkling oyster shell along the fence of the run, and they started laying, like, the NEXT day! I noticed some of those first eggs had shells that were "wrinkled," and noticed them get stronger after a few days. So I now offer oyster shell daily when I feed, and am back to enjoying an egg bounty!
