The most important things is that you keep your head up asher... Honestly, some people take breakups really badly and while it is okay to feel sad don't let it damage possibilities for future relationships with other girls because you look sad and depressed. Take your time, just go day to day and keep your head up. Eventually, it will pass and you will be thinking about a different girl... Just keep your head up.

What if I can't think about any other girl? The girl I'm interested in has been on my mind for weeks now.
Well, I guess one will pop-up one day or another..

Trust me that it takes time, how much depends on the person and seriousness of the relationship... you just have to remind yourself that you don't need her to be you and that if she doesn't want to date you then it is her loss and that you will find someone better in the end. Not only do you have to say that to yourself, you have to believe it... Everything works out in the end, you just have to have trust.