A break up can be difficult, but there is nothing else to do but to move forward and learn from it. There are only three scenarios; your at fault, she's at fault, or you're both at fault. Usually there is a bit of blame on both sides.
If you believe that you're at fault, reflect back on what you may have done wrong (this can encompass a lot). A surprising number of guys believe that the hard part is getting the girl, but relationships take a lot more work.
If both of you are at fault, I'd suggest better communication.
If its her fault there is really nothing you can do except look within and ask yourself why you were attracted to her in the first place. This is a really deep question that stretches back to your infant years.
A brake up is not all bad, now you have the time to pursue your hobbies, spend time with friends and, most importantly, find yourself.
I know this is a very short answer, but I did not want to end up writing multiple pages- I'll leave that to you guys. However, I can make a post going in depth and analyzing various studies regarding break up recovery. If you think that will be valuable let me know.