How to persuade my mother?

First it depends on how old you are, whether or not your mom is right in telling you no. And I would go see a physician and see what they tell you to do before taking some random vitamins to try and help make your hair grow. (not all vitamins are good for you) Plus I have heard about some hair vitamins that do work and make your hair grow, but the hair is brittle and thin, and it causes more problems than it fixes...