A Hopeless Cause: Diagnosis

Two years ago, Maddison Grey was on the way home from her dance recital, her parents and four year old sister in the car with her. An intoxicated semi-truck driver switched lanes then, going the wrong direction. The semi crashed head on into the Grey's car, instantly killing Maddison's mom and dad. Her sister made it out alive, along with Maddison, but died that night. Maddison lived. The only weird thing is, Maddison cant remember anything.
Now, two years later, Maddison lives with her aunt and uncle, two very important people in her life. They constantly have to remind of her of that night, two years ago, thinking they could somehow make her remember. But Maddison just wont budge. She cant remember a thing, and now......she seems to not worry about it. At home, shes quiet boring Maddison, but after dark, she owns the night. Drinking, partying, and guys are the only thing that matter to her, instead of good grades, family, and dancing. Something changed Maddison that night, but she needs to figure out, before she hurts herself or the people around her.