I am having some problem in my left knee after my accident on my Bullet bike. I fall down on my Left knee and after that it's not good.

Question

Hamstring Stretch
Lie on your back with your left leg flat on the floor. Loop a towel or rope around your right foot and pull your leg as far as comfortable toward your chest, while keeping a slight bend at the knee. Keep your back pressed to the floor throughout the stretch. Hold for 10 to 30 seconds and then release. Repeat 3 or 4 times with each leg. Do this stretch 5 or 6 times a week.
Short-Arc Knee Extensions
In the same starting position as the straight-leg raises, put a ball (about the size of a basketball) under your left knee so that your leg is bent. Slowly straighten your leg. Hold, then slowly lower. Repeat with your right leg.
Exercises To Avoid
A few of the following exercises can be done safely if you have chronic knee problems; they're on this list because they're more likely to be done improperly. The exercises above are safer, while still giving you similar results.
?Full-arc knee extensions
?Lunges
?Deep squats
?Hurdler's stretches.

Sonia Sharma · Accepted Answer

Hamstring Stretch
Lie on your back with your left leg flat on the floor. Loop a towel or rope around your right foot and pull your leg as far as comfortable toward your chest, while keeping a slight bend at the knee. Keep your back pressed to the floor throughout the stretch. Hold for 10 to 30 seconds and then release. Repeat 3 or 4 times with each leg. Do this stretch 5 or 6 times a week.
Short-Arc Knee Extensions
In the same starting position as the straight-leg raises, put a ball (about the size of a basketball) under your left knee so that your leg is bent. Slowly straighten your leg. Hold, then slowly lower. Repeat with your right leg.
Exercises To Avoid
A few of the following exercises can be done safely if you have chronic knee problems; they're on this list because they're more likely to be done improperly. The exercises above are safer, while still giving you similar results.
?Full-arc knee extensions
?Lunges
?Deep squats
?Hurdler's stretches.