How to grow hair longer?

Ok so my hair is medium sized it's passed my shoulder and i was wondering if there was a way to grow my hair out in a few weeks because I really wanted long hair for the dance so do u have any ideas pls and if there isn't but u know about hair extensions can u give me some stores where u can buy 18 inch hair extension that aren't that expensiveand can u pls give me the price of the hair extensions pls btw I live in arroyo grande zip:93420 Plz I don't care if it's fake hair or real because it's only for one night