I say you should get some more chickens the same age/size and put them in like a water trough or dog cage and put a brooder lamp on it. Or you should give it to the neighbor because your neighbor has chicks!! Good Luck!
It took my Rhode Island Red's a little bit longer to start laying but when they do start you will have some really nice eggs. I have a question, Do you let your chickens free-range? Once you answer that I will know for sure what's wrong.
I have had help by just looking up ways to help something. I always end up going to this website. If I give advice please take it to consideration because I know what I am talking about! GO CHICKENS AND DUCKS!!!