You can order the flaps off Amazon. They are flaps to cover a dog house opening. Search dog houses and there should be flaps there. I ordered a dog house for my ducks and the flaps were an additional option for 10$.
Please take your duck to a veterinarian who can evaluate her condition. She probably needs some antibiotics and pain medications. Being that ducks will hide their illness to keep from becoming a victim of prey, showing weakness ensures they will be eaten. Usually by the time you noticeably...