If you do want your ex girlfriend back, you must first understand that this is a very delicate situation.
Appreciate the fact that both you feelings may be hurt.
The more careful you are about this, the better.
Otherwise feelings may be hurt even worse making it near impossible to get your ex girlfriend back.
Here are the some things you must consider if you want to get her back:

• First and foremost, what caused the break up? It does not just happen.
  Do not be deceived by the reason that seems apparent or obvious.
  Find the real underlying reason behind the break up even if you are not immediately aware of what it is.
  The essential first step in this process to get your ex girlfriend back is for you to figure out what went wrong, whether or not it could have been prevented, and how can you can fix it now that you know what it is.
  
• If the break up with your ex girlfriend was entirely your fault, then you need to help rekindle things.
  Let your ex girlfriend know that you recognize what happened, acknowledge that it was your fault, and apologize for your actions and their unintended consequences.
  
• Carry on socializing with other people, even though you are trying to get your ex girlfriend back.
  Just because you and your ex are not in contact right now, it does not mean that you need to cut yourself off from the rest of civilization.
  Date another girl, or at least go out and have some fun with your friends.
  It may even work in your favor as it may cause some jealousy in your ex partner.
  
• Show your ex that you have moved on.
  However, you also need to show her that you still care about her.
  This is the best way to eventually get your ex girlfriend back.
  Let her know that you have not completely abandoned her and that you still have feelings for her.
  You will appear more mature as well as desirable to her.
  
• You must be prepared to work to get your ex girlfriend back.
  It is a process that must be given time to work.
  You have to rebuild trust and reconnect in the right way.
  

Find out what is the process that you must put in place to get your ex girlfriend back.
It includes identifying problems and continuous improvements.
There must be an action plan with a meaningful schedule that you can implement.
Learn how others have been successful and use it to get your ex girlfriend back.