Well all it depends which type of rejection are you facing.
In general the time is the best healer and you can get normal with the passage of time.
Here are few tips that could be helpful in such situation:-
Have faith that something more better is waiting for you.
Keep the believe that it will got better.
Have some positive physical activities.
Discover something new or engage yourself in some new project or activity.
Sometime traveling way may also be helpful.
Try to increase your social circle.
If you have some close friend to whom you can trust, do get help from him/her.