Your state of mind after a serious breakup cannot really be described effectively with words, suffice it to say that you feel absolutely shattered, depressed and if the case be, rejected. More so if the relationship had been lasting for some time. Not only is it difficult to recover from this state, but dating again is probably the last thing you are thinking of!
However, it is important to overcome this phase, take time to let out any anger, disappointment and give yourself a time to 'mourn' your loss, you will need this period of time to be able to fully leave this difficult trial in your life behind. This period should also be constructive, you should allow yourself some time to ponder over your past relationship and try to understand what went wrong. Do not blame it all on your past partner, try and be objective, although it may seem difficult at first. Run through this period and try and admit to any faults in your behavior as well, this will help you for your next relationship and will also make you feel better and less rejected.
Once you've given yourself time to adjust and reflect over past events, then, just then, you can move on and consider dating again. Do not make the mistake of launching prematurely into a new relationship, in order to forget the last one, not only will it be a disaster, but it will also be unfair to your new partner.
Once you've started dating again, do not make the mistake of talking about your past relationship ship with your new partner and do not rush headfirst into this new experience. Give yourself time, enjoy your dating, go out to places where you can have fun and be carefree, do not plan anything serious for the future, just take it a step at a time.
When you start dating again, it is crucial you don't stereotype your partner, just because you were let down once, it doesn't mean everyone is the same. Most important of all do not feel you have to date again straight away, if you're not ready don't, there is plenty of time ahead, and most importantly don't let others put pressure on you.
At times your family and friends may be eager to help you recover and may be intrusive, although they are doing it because they care, let them know that you aren't ready yet. What can be of help, is getting out together with your friends, this will help you pick up your spirits again. Enjoy your new freedom and independence, take advantage of the fact that you can choose at your whim, do not let this state get the better of you, sometimes being alone really helps us mature and understand what we really are looking for in a relationship, it helps us be ourselves again.