be nice to her, and well if that doesnt work i dont know what to tell you , but make sure she knows that your being serious when your nice most guys are rude and are sarcastic when they say nice things to girls ahha,
Try talking with her privately, and ask her if you can start over and be friends, or at least be nice to each other in passing. If she's not willing to let whatever she's got against you go, she's not worth your time. Be yourself, and if you are a positive, confident person who is kind to others maybe she'll eventually come around. If not, forgive and forget her. She probably has some underlying deep issues that cause her to feel so negatively towards people. Be happy knowing you're a good person.
You can't do anything. She may come around, she may not. If she doesn't then it's her loss. If she does then good for you! Just be nice when you have to be around her, and ignore her otherwise. If you try to hard she will just get more annoyed.
you should just be your self, dont try to hard! if you think she hates for something you did or said, and is not even important, she will get over it, just dont give to much attention to it! she will notice! good luck!