Going through a break up with your girlfriend can be both confusing and emotional. You may want to get your ex back but are not sure how to approach them because of mixed signals. Until you have those mixed signals figured out you will have to put off trying to get her back.
When the two of you were still together did she give you any clues as to any problems. In fact who's idea was it to break up in the first place. If it was her you need to find out exactly why. You can't go about getting her back without all the info you need so you can formulate a plan.
If you were the one to initiate the break up why did you do it and why do you want her back now? No matter why any break up happens, both the guy and girl are upset over it. I you initiated this break up your ex girlfriend is going to be really pissed off at you. This makes the challenge that more difficult.
You may have second thoughts after breaking up realizing how much you care about her or realized you made a mistake, the reason for breaking up turned out to be trivial. You will need to apologize to her from the heart stating you made a mistake and ask for forgiveness. She may not want to talk to you but at least apologizing would be a good start.
Give her time to think things over and do not hound her, begging her to come back. You will look pathetic to her and may push her away. Give it a few weeks time for her to get over it, you can at least call her a couple times to see how she is doing and nothing more. Again don't push the issue.
After a few weeks call her and ask if she would be willing to meet you at some neutral location for coffee. If she says yes then you may have a good chance with her. Keep the meeting short and ask her what the chance is at getting back together. She will tell what she thinks, and hopefully you can meet again at a later time the same way as this first.