What is the name of this movie?

I remember this movie I saw a few years back, it was about this girl who got hit by a car, and her "ghost" meets this guy. However, the ghost doesn't remember who she is. They fall in love, but when the girl wakes up from her coma, she doesn't remember the guy. There was a scene where the two work together to save this guy's life, and stab him with a ballpoint pen.