MY CHICKENS HAVE STOPPED LAYING

They might be "laying away" which means laying somewhere other than the nest box. Have a good search round and you might find a stash

If they have bare bottoms they could be feather pecking so get some purple spray and use it if you see any bare flesh as they will peck horribly. Check for visible signs of any insects - both on the hens and in their housing as they can get lice and mites. It's just a case of being vigilant and keeping things clean. Clear out poops daily in the housing and runs

Are they being fed layers pellets? Sounds obvious but you'd be surprised how many aren't    they need a good diet of the layers pellets and fresh greens, clean water daily or more in warm weather