Possible prolapse

Sounds like a prolapse.  Some people put them in a warm bath, push it back in gently and apply anulsol cream.  While it may work temporarily, as soon as they lay an egg again there is a chance it will happen again.  Chickens being chickens will peck at red things and it can soon become a blooming mess and in my opinion the kindest thing to do is to dispatch the hen before she gets pecked.