When do sprained knees heal?

Exactly Eight weeks ago i sprained my knee skateboarding,I went to the doctors the same week and he told me it should heal in a week,which it did.I read online it takes six weeks for a sprained knee to heal but not fully.now its been eight.so is my knee ready yet?how do i know when its ready for me to get back into sports?am i gonna miss out the whole summer?:/ by the way i can walk.i just haven't tried running and jumping yet.