Hi,I'm just 21 years old boy... lots of friend beard facial hair... but me not... I have already do some exercise... shave regularly like often 3 days after... takes biotin... but didn't get result... my friends are now irritate me... I m so upset... plz help me what I do??

Maturity is the only sure fire method although some men never have reliable facial hair growth.
Ask your father when/if he started growing a successful beard.