I sprained my ankle 6 months ago and it still hasnt healed why?

You probably fractured it. The same thing happened to me. Then, years later I broke it for sure, and when they X-rayed it then, they found the previous fracture which had never been corrected. Now my ankle is seriously weak for life, and it's going to be hell when I'm older. I'd get it looked at if I were you, before you break it badly because it's now weak.