If you are wanting to know how to get back together with ex partner, then do not lose heart and write the relationship off.
Just because he or she might have left you does not mean that you can't rekindle those old feelings you both had when you started out together.
Part of the process is to figure out just what went wrong.
Were you in any way to blame? Would you do things differently given a second chance? If you feel that your behaviour was a factor, then write to your ex explaining that you are really sorry and give him or her a full apology.
Explain that you know where you went wrong and that you would not let that happen again.
If your partner seemed to have changed (perhaps they seemed bored or disinterested) then try to discover a way of changing things.
Trying to get things back to how they were is not a good option, your ex needs to see a favorable change which makes them long for the person you have become rather than the person you were which, for whatever reason, they were not happy with.
Whatever you do, make it clear in the letter that you will not be making contact again and leave the ball in their court.
Do not appear to be needy-in fact one of the best things you can do if you want to know how to get back together with ex partner is to appear independent and "in demand".
Try to develop activities which are different to those you enjoyed with your ex.
Also, when contact is made, suggest a short meeting, such as a quick coffee after work rather than a full-blown evening together.
Remember that if you want to know how to get back together with ex partner, then remembering the great times is a good way of reconnecting.
When you do meet up, a couple of "thrown in" reminiscent memories will do no harm-providing they are good memories for both of you.