Wizards of Waverly Place Season 3 Episode 24 : All About You-Niverse

Alex is punished for buying a vending machine with her parents money. Alex sees a mirror that says "Do Not Go In Alex". After Alex steps through a magical mirror, the universe becomes all about her, and when the mirror breaks after she doesn't want to come back to the real world, Alex is possibly stuck in the parallel 'you-niverse' forever.