Your boyfriend told you he needed space and then he was gone. He gave no reason and did not act as if you cared how much he was hurting you. But, you still love him and want him back. If that is what you want, then you have to make your ex boyfriend regret leaving you. When he does, he will love you again. This will pull him back fast.
First of all, you will have to avoid the mistake of pushing him farther away. This is no time to be trying to get him to talk things over. Any contact with him at this time will only result in more rejection and hurt for you. It is too soon after the breakup to make him change his mind, so don't try. Do not give him the satisfaction of seeing you crying and begging. Your focus should be on making him regret leaving you.
Your ex boyfriend is still in love with you. Love does not just die in an instant, so to make him regret leaving you, make him think he has lost you. That will require you to give him the impression that you have accepted the breakup and you are moving on. The best way to do that is to stop having any contact with him. This will allow you to get a grip on your emotions and let him experience his life without you. He will also be thinking you do not care for him anymore.
Taking this sort of action will be contrary to what he expected you to do. By ignoring him and going about your life as if he does not exist, you are making him feel rejected. He was sure you would be sitting around waiting for his call, but now he is starting to regret the breakup. If a couple of weeks have passed since he announced he needed space, you should have a grip on your emotions.
This would be a good time to make him sure that he might lose you.