How do I get back into my itunes store account?

Help!!! Whenever I try to buy something on the itunes store it says my accounts been closed for security reasons. I know why, its because my sister tried to get into my account to buy something with my money. I want to buy some things but I can't get back in. Please tell me how to get back in!!!!|||You'll have to contact Apple support.|||You can email iTunes customer support. They should be able to help you reset everything so that you can access your account again.