How can i regain my height lose due to hookah smoking daily at 16? i'm 21 now and still look like a 16 yo, have pubes. can i still grow? some meds?

Unlikely: At your age, it is almost impossible if not outright impossible to gain height. You stunted your growth during the last year or two you had available to your body, and now it is too late. I'm glad you have seen the light and stopped smoking hookah, but the window of opportunity passed and now you will have to live with those results. Bulk up muscle with exercise and move on with life.

Probably not: If one has delayed onset of puberty, than further growth is sometimes possible. However, at your age, further increase in height is highly unlikely due to closure of growth plates.