Even though your heart feels as if it is being torn apart, and you so badly want to contact your ex and tell him/her that you love them so much, and desperately want him/her back in your life, DON'T do it! This is really the last thing you want to do now, to win your ex back.
All your ex wants to do is to get over the hurt and anger of the break-up, and not be reminded about all the pain that was caused when the relationship fell apart.
This can only be possible if he/she has sufficient time to deal with all these problems.
Some time away from your ex will also help you tremendously as well.
Once you are over all the hurt and anger of the break-up, you will be in a much better frame of mind, and more capable of talking things over with your ex in a calm, friendly manner.
This approach to the situation will give you a much better chance to win your ex back and possibly get back together again.
Use this time to think about what is was that you said or did that could have played a part in the cause of the break-up, and make an effort to rectify these problems, if any.
This will not only help a lot if and when you and your ex do get back together again, but will also make you feel a whole lot better as a person as well.
Once you realise that your ex feels just as badly as you do, you will understand the necessity to be away from each other for a while, in order to deal with the problems effectively.
However, don't sit around waiting for time to pass, get in touch with your friends, and enjoy your life as much as you can.
You will probably win your ex back, just by being you, only happier, and someone he/she will only be too pleased to be with once again.