She's the Man (2006)

Viola Hastings is a teen girl who plays for Cornwall’s soccer team until the team gets cut. Meanwhile, her twin brother, Sebastian, is supposed to enroll in Illyria, an elite boarding school, but he secretly goes to London with his fledgling band instead. Viola agrees to cover for him and decides to pass herself off as Sebastian, in hopes of joining their boys' team and beating Cornwall to prove their coach and her cocky ex-boyfriend, Justin, wrong. With the help of her stylist friend, Paul, she is transformed into "Sebastian" and attends Illyria in his place.