Hello. You may have a dislocated patella which is a bone in knee. But there is nothing to worry because strengthening of your thigh and leg muscles can help. Which will strengthen all muscles around knee joint. You have to sit on a bed and let your legs hang from the egde and put your hand on thigh and raise your leg against a slight resistance of your hand. Kindly abstain yourself from too much walking and weight lifting. If it doesn't help then you have to get a cast around knee joint and seek advice from an orthopedic surgeon.Hope that answer the question. Thanks