I have a friend who when she gets mad she walks off and she would not talk to me what should I do?
you realize a TRUE friend wouldn't do that.
she is probably not your friend and she is just manipulating you
Maybe she does not like confrontation ? Or has anger issues, best ask her yourself if that particular behaviour offends you.
Wait till she's ready to act like a big girl and sit down and discuss it. If she doesn't, then look for a new friend that can be a real friend.
beat her ass
ask a counselor
She is not a true friend and if she tries to be your friend later on tell her NO!
Well think about what she gets mad at you for. If it's something she may be jealous of then try talking to her about, but if she gets upset all the time then it can't be something you did it's her.