There are different grades of sprains, so it kind of depends on how bad you did it.
First off, RICE for the first few days.
Rest
Ice
Compression
Elevation
Look it up if you don't know what I'm talking about. After the first few days, most basic sprains will start to get better. However, a sever one could take up to 6 weeks or more. The important thing is don't push it till it's ready or you'll just damage it further. Pain is your indicator. If it hurts or feels unstable, don't do it.
One more thing, if it is a pretty bad sprain, you may want to get it x-rayed. In some sprain cases you will also crack some of the bones in your ankle and if you don't take proper care of them, you could end up needing a fused ankle or an ankle replacement. Blood flow is low in the ankle bones and if you keep pounding them while they are trying to heal, the bone can die. That's a road you don't want to go down.
Anyway, good luck and hope it gets better soon.