What can be more regretful, than trying to get your ex back, and then finding out afterward that everything you did only repelled your ex away! The last thing you want, is for your ex to hate you, so I suggest you stop doing these deadly blunders right now if you really want to pull your ex back..
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Calling your ex like crazy - he/she just wants some space, and there is nothing more annoying than having the phone ring and ring and ring and ...
you get the point! It makes you look desperate and like you are trying to force him/her to talk to you and take you back, it's just not cool, so give some space.
Arguing with your ex - When they don't take you back, you immediately feel offended and like all of your efforts were wasted.
You feel rejected, and then your ego comes in and says "hey wait a minute, he/she can't just reject me like this!" So then you argue.
All this does is makes your ex's defenses go up, and like calling your ex, it also makes your ex feel like he/she is being forced.
Trying to make your ex feel guilty for not having you - When you do this, you come across as being so obvious, that your ex will just laugh and then think you are pathetic.
You cannot just go up to someone and say "you better take me back, because you won't find anything better" or "I will hurt myself if you don't take me back".
Do not say anything that even remotely attempts to make your ex feel guilty for not being with you, because it will always backfire.
Your ex will feel a need to prove you wrong, and prove that they do not need to take you back, when you say things like that.