Hi doc...i am a 20yr old boy and my height is 5 ft...can i increase my height now?

Not really possible: When a boy enters puberty and begins changing, a process takes place in the long bones which leads to the closure of "growth plates." This closure of growth plates is irreversible, and when it is complete, the bones can no longer grow. When the bones stop growing, it is essentially impossible to achieve any increase in stature. If you are 20 years old, you likely have no more height potential.