Welcome to BYC. How is she standing or walking? Does she hold the leg up, walk on it, or is the leg stuck out in an odd position? Can you see any swelling, redness, or bruising on the leg or foot? Can you look at her foot pad for any cuts or sores? Resting her leg in a crate or cage near the other chickens would help her to remain part of the flock while she heals. Put her own food and water in there. It can take 2-3 weeks for a bad sprain or a broken bone to heal. Splinting may help if it is broken. Large animal vets will sometimes see chickens if they are familiar with them.