Sorry to hear about that. That situation has been my biggest fear about raising chicks. Since I sometimes get back from work quite late, I installed a solar powered, light activated, automatic pop door on my coop. The chicks go in before dark and the door closes about 30 minutes after dark. It then opens at dawn before the chicks and I am up.
I also have my mobile coop, which I move about the pasture for free ranging, surrounded by solar powered electric netting fence to keep out predators, so they have double protection. I still go out every morning to feed and water them and do a head count, just in case. Raising animals can be a rewarding task and sometimes heart breaking but we still love it.