I don't usually like to teach these kinds of things but people ask me this too much. I recommend that if you're going to do this, do this on the right people because some people are very vindictive. People have very long memories and may try to get revenge on you years later. I usually recommend getting over people you lost but if you're really persistent, let's get started.
So here's how you make anybody regret losing you. First things first, if he dumped you or you dumped him, people always come back so don't block them because it looks emotional. Generally, blocking is petty and it gives away all your power especially if you're doing it to get a response.
There are two reasons that you got dumped, one is you're emotionally weak or two, he's not attracted to you anymore.
Why were you weak emotionally? It's because you're reactive to him and you're too available. The unattractive part is not because you're unattractive, it's because of you either let yourself go or you're too familiar to him.
The solution is creating space and saying no. Keeping distance shows strength. Show strength by when he does contact you, you're polite but distant. To do this, you have to take a long time to respond to him but in a very polite way. This is passive-aggressive and it annoys people. This type of annoyance hurts guys egos.
Show strength by emotionally not being affected by him. Let him have the last word. If somebody bumps you, don't ask why and let them go, it shows strength.
The next one is the pre-selection. You got to put guys in a sexually competitive state. Most women want to satisfy their men so much that they hide the attention other guys give them. So put that in their heart, they got to have a threat. Also, make sure you're doing things so people will fill in the blank.
Another thing is to always hit the gym and get in shape. The way that a guy gets over a woman is if she gets fat. The more that you don't care about yourself, the easier it will be to get over you. So go to the gym, get in shape and let the results show. Don't advertise it, let people be surprised.
If he wants you to come back, just say "I don't know about this" and tell him thinking back you don't like his personality and don't tell him why. By not telling him why, it will annoy him and make him think.
We discuss this in greater detail in my course.... click here.