The question at the top of everyone's mind who's just been through a rough breakup: is it too late? Those four words can haunt you and destroy you...but the answer to the question is a bit more positive.
The truth is, very few relationships are doomed just because of a breakup...many of them still have a very legitimate chance to be pulled back together, you just need to know what you're doing. Going into this without a plan would be very costly, but 90% of all broken-up relationships can still be pulled back together.
The question you need to ask yourself, however...is do you WANT your ex back. Sometimes people split for genuine reasons, and not every time is it really the best idea to get back together at all...but often we're just so caught up in the dismay at being alone again that we forget what drove us apart.
So do you still love your ex, or do you love the safety and comfort of simply being in a relationship? It may not be your ex you want back, but the stability of being in a steady relationship...and you could be just as happy if not happier with someone more compatible with you.
However, that's not the case for everyone...sometimes we just have problems and if they're worked out, the relationship can be saved and better than ever. So if you discover you really do want your ex back, I advise you to seek out some help figuring out a plan to do it. It's not too late, you just have to know what you're after and how to get it!