I want to increase my height.. i am 5 feet and 0.5 inches....and i m 20 years .. is it possible?

Growth very unlikely: A 20 yr old is not growing taller if his growth plates have fused. If not fused, he will grow a tiny bit (pediatrician's growth chart for him can tell if growth has stopped). To look taller, one can choose properly designed clothing & shoes, and have good posture. Vitamins, supplements, "special" foods, extra exercise, etc... will not make a person taller if he already closed his growth plates.