I banged my knee in my kitchen two days ago. Have swelling and difficulty walking on stairs only. Using ice and naproxen. How long for swelling to go.

Swollen knee. Usually in 48 hours you should see a significant reduction in swelling. Especially in combination with an NSAID. But if you are an active person and don't allow yourself time to rest and keep your leg elevated then it will be longer. It also depends on the severity of the injury. If you have a fracture, it will be longer. Given your age I would probably talk to your doctor about it.