Help about disney movie?!?!?!?

Disney movie where the girl at the beginning she's singing and playing guitar dressed in a cowgirl outfit with cow print vest, she gets into a music school where her mother can't even afford and just lies and says she can, and at the end, she's singing the Carmen opera and then busts out in english with the carmen opera tune. ANYONE KNOW WHAT IM TALKING ABOUT!?!?! i can't find it anywhereeeee