Lost her mind

This girl I know had a little to much fun. She drank,she took drugs but a little to much. No one knows why?
She had got memory lost and could remember nothing. She is one of my best friends. She tends to be center of atention and when she's not she will do anything to get it.
She didn't remember anyone not even me. I was one of her best friends and all she could say is "you look familiar," I just wanted to scream and yell how could you.
But I could say nothing. How could I she wouldn't even understand me.
But the horrible thing was after she took those drugs she tried to kill herself. I though to myself what kind of friend am I how could I not know how she felt. She is ok and well.
But how could she. she's only fourteen. How can she feel that way!