OK so everyone seems to have some sort of opinion on how to get your ex back. Well I'm going to stay away from philosophy and give you some facts that will actually help you get back with them. Let's look at things the Steve Jobs way and keep things simple. What was the reason for the break up? Did you cheat, lie, stop communicating, or say the wrong things. Let's start with cheating.
Cheating is one of the big reasons why people break up. It eradicates the trust in a relationship making things very difficult for people to want to stick around. OK so you made a mistake and cheated and now you're wondering how to fix things. First take a hard look at yourself and consider what caused you to cheat. Was it that you needed more physical attention or that your partner was driving you away? If it was either of these two then you made a mistake. Instead of cheating you should have talked with your partner about the issues at hand. Communication is key and I cannot stress this enough. When you begin attempting to get back with your ex, make sure you explain why it is that you cheated. This can't be some BS answer talking about how you were drunk and made a mistake. No, that doesn't cut it, and will not help your situation. There are plenty of married people who get drunk with friends and never cheat. Be honest with them and I promise you that the conversation will go a lot smoother.
Lying is another big reason for break ups and this is tied into with cheating. Lying makes it near impossible for your partner to ever feel comfortable. For them, it's like a constant anxiety attack and this can immediately drive them away. So, when you begin communication with your ex again, which shouldn't be for a couple weeks or so, make sure and explain why it is that you were lying. Was it because you felt they wouldn't want you to be at a certain place or hanging out with certain friends? Whatever the case may be, make sure to explain this to them. Do not make excuses about why you did it. A simple honest explanation will do.
As you can see majority of these issues are caused due to a lack of communication. No matter what you did wrong I'm willing to bet that you were not properly communicating. I also need you to understand that there were probably some things that you thought you were doing correctly, but was actually a mistake. For example, always saying sorry and telling your partner how you are meant to be together.
The reason you shouldn't be telling your partner why you are meant to be together is for the mere fact that this is something they should figure out on their own. Not something that is being drilled into their head.