Whatever it is, if you can, take a few hours not to have it in your mind all the time because it doesn't help, instead, put on a song that you like, find something to eat that you like a lot and do something that distracts you from that event that saddened you (such as drawing or playing). Remember that it is important the less you think about it the better and if it is difficult for you, DO something, it usually works because you keep focused on something else, just that... I hope something makes you rejoice a little and soon you feel better!

Thank you
Love you