I've had the side of a chair fall onto my foot. its a bit swollen and painful. what shall i do?

Get an X-ray.: If a chair fell on your foot and it hurts that much, you may have a broken bone in there. An X-ray would be helpful to make sure.

Injury: if you an walk on it it is probably not broken. If the pain persists or gets worse then let your doctor have a look as you may need an x-ray. You can try moist heat applications, that might help