knee length hair - picture of long hair lady from Russia
There is a vitamin called Biotin, it is a B vitamin that helps your hair and nails grow healthy and the hair actually grows almost twice as fast. You can purchase biotin anywhere you buy vitamins. Avoid prenatal pills if you can, the only thing that helps your hair in that is the B vitamins, so you might as well just take the simpler form. Prenatal pills have been known to make people ill if they don't need all that.
Biotin is not a guaranteed speedy hair growth solution, but it is known to help.