Fell down the stairs 2weeks ago and hurt my ankle. It does not hurt much to try to walk, but my ankle is bruised and swollen. When will it go down?

Body says "unstable" The swelling is the body's way of trying to control the instability of the ankle due to the fall. The bruise is the from initial bleeding and now slowly changing color as the blood is being resorbed. You are going to have to use some type of brace to stabilize the ankle. You might consider having it evaluated just to make sure serious damage did not occur during the fall.