Most Helpful Girl
Try writing her a letter. Letters are advantageous because you can say everything you want to say and she can read it whenever she wants and she has to listen, she can't argue back. If you actually did hurt her feelings, make you you apologize sincerely and explain that you really want to work things out with her and all that. After you deliver it, it's up to her to do what she wants, whether it's meet up with you to talk, forgive you, break up with you, whatever... but at least you'll have done everything you can.
Most Helpful Guy
Whether or not you can get her back depends on the magnitude of what you have done and how much it hurt her. If you hurt her badly then you might not get a second chance. That's why we need to think about what we do BEFORE we do it, because we don't always get to try again.
If she won't talk to you then you have no avenues in which to do anything. All that you can do is to get on with your life and work on improving yourself.