I really hate to say this, but anytime mine have gone missing, I find them in the woods or pasture a few days later, or at least what is left of them. Hawks owls and eagles are a big problem for me, idk about you. But winged predators seem to be in more places than ones that can't fly! If a chicken knows where their food, water, and nest is they usually come back for one of those 3 things. Unless she could have possibly gone broody on you, and in that case, I'd be looking anywhere underneath bushes, shrubs, or anywhere that looks like a chicken could get under it and lay eggs and be concealed. I have never had a chicken wander off very far from their coop. They seem to know where their bread is buttered at my house! I hope you find your girl!!