We haven't had this problem. But they are safer locked up in the coop at night. Our chickens free range our back yard a lot of the day (2-3 hrs in the morning and the same again in the afternoon). Yesterday they were attacked by some very large bird, possibly a cooper's hawk. Fortunately the chickens made a ton of noise and flapping and ran under the deck and they were all ok. But it is a dangerous world out there for big heavy birds that don't run very fast or fly very well.
When we first got them as little chicks we had to train them to go up on the roosting bars at night. We just physically put them there every night and closed the door so they had to stay in there. Didn't take very long for them to get used to it. Then we left the door open, so they could come down into the coop and run (all enclosed and protected from predators) first thing in the AM for food and water, without us having to get up and release them. You might need to do something like that again.
Our chickie ladies are also trained to come to us. We get little bags of mixed seed and fruit treats that they love. They know the sound of the bag being shaken and come running. They also know the bags are stored in the shed and come running to the shed if we walk towards it. At this point, they come running to us to be petted anyway, regardless of treats and follow us around the yard. They are very curious about us and like to come up on the deck and peek in through the glass door and see what we are doing. One in particular would love to be a house chicken, but we aren't ready to deal with chicken diapers!
(They actually make such a thing, so I guess some people must have indoor chickens!).
And if there is a way out of the coop, you have to get someone to help you seal it up. The chickens do like to pop out of any available hole.