What Causes Numb, Cold Hands And Feet?

Hello I am a 17 nearly 18 year old female and my concern is that my legs, feet and hands feel cold at all times, even if i do work out for body, but sometimes my feets and legs feel numb. One more thing when I was 12 years old I broke my ankle by having a car accident. My feets were under tires and the numbness started from that time. Thank You and I am waiting for my responds.