If your girlfriend left you and all you feel is a feeling of sadness and depression you should pay close attention to what I'm about to reveal to you.
When you're right in the middle of a breakup, you probably feel an overwhelming amount of different emotions.
The one moment you feel confused and the other you feel hatred.
That's perfectly normal and just a process you're going trough to get on with your life.
For some it takes a few days, while it can take many years for others.
However, if you want your ex girlfriend back, these changes of emotions doesn't help you at all.
When you're happy one moment and sad the next, your ex will become confused as well and before you know it, you'll had pushed her farther away from you and limited your chances of ever getting her back.
Instead you need to learn how to control your emotions.
If you can master how you feel (or at least how you appear to feel) you'll see stable to your ex and that will allow her to get attracted to you once again.
The real problem with all of this is, that the reason you cannot control your emotions, is because you have no clue on how you should get her back.
One moment you think you know exactly what to do, and therefore you are full of confidence and self esteem.
But when you realize that the stuff you thought would work doesn't or when your ex is testing you to see if you are for real, then you break down again and get all depressed and sad on her.
The cure for all of this is simply to develop a confident attitude that'll show your ex that you're in control over your own feelings and the situation.
The easiest way to develop such an attitude and to get your head straight is to learn all about how to get an ex back.
You could buy a guide or talk to a close friend.
Whatever you choose to do, the important part is that you lay a long term strategy for winning her back.