How do i get my hair to grow faster?

Like REALLY REALLY FAST. :O I cut my hair wrongly and i need my fringe and back to grow at least 3 cm before school starts, which means only 10 days. Maybe it's impossible to grow THAT fast, but please give me some advice! I am really desperate. I don't feel like going to school like this :( Oh and please tell me ways that i can do by myself and don't have to buy anything in order to do it :) Thanks