If your girlfriend broke up with you, odds are you did something wrong. It might be difficult to admit it but look hard at what may have led up to this so you can determine exactly what happened. If you can't figure it out ask your ex. At some point you will be able to talk to her again so ask her what you did to cause a break up.
If you decide you want to try to get her back you will need to know the answer so you will know what to do to make things right. Don't have an attitude with her, be polite when you talk, otherwise she may just blow you off. She may be more than happy to explain why she left you. Listen carefully to what see tells you and if you think she is wrong don't argue with her.
Whatever it was then you must apologies and do whatever you can to make the changes necessary to appease her, this you must do if you want to get her back. Also consider some other things you can do to make things better such as paying more attention to your girlfriend. This is not an unreasonable request and will make her appreciate you more for showing more interest in her.
