Sometimes relationships come to an end prior to the time a person feels it should. In that case people try to do almost anything to repair and salvage that relationship. Sometimes they try to get an ex back fast when they really need time to sort through things. To mend a relationship it may require change in yourself or in your other half.
The first thing you should do to get an ex back fast is examine the relationship you had with them. You will never be able to fix what went wrong if you don't even know what it is. Sometimes you may not understand what it is, in that case you should confront the ex about that. After the relationship examination, you should ask yourself what you could of done better or different. Often times, you may realize your own selfishness got in the way, learn how to let that go. Then you need to know what your issues are with the relationship and your partners issues are as well, only then can it be changed. Remember, communication is the golden key. Be willing to talk about these problems that's the only way the relationship will work.
Once you and also your partner have examined and discussed what is wrong, you have to compromise. Neither of you are ever going to get exactly what you wish for, it just doesn't work that way. So you have to be willing to let go of somethings, it is perfectly fine to stick with the more important aspects you wish to be changed. However, if you are getting mad all the time because he or she doesn't do the laundry or call your mother you have to be willing to let that go. It will only cause conflict that isn't necessary.
To conclude, if you are old enough to have a relationship, you should be mature in that relationship. To get ex back fast, you have to work through problems with yourself and your partner. If you are not happy your relationship will not be a happy one either.