distract yourself. this is very challenging, i understand, but it's much better than pondering on depressing or fearful thoughts. do everything you can to stop thinking about things that make you upset and unhappy because that will get you nowhere.
watch a funny video, write a story, consult a friend, draw a picture, try new things. do something to get your mind off. again, this is very difficult, but everyone pulls through in the end, even when the light seems very far away.
listen to happier songs. listen to the music that can put you at ease, and to music that will lighten your mood. music changes and shapes your view of the world drastically, and it's not helpful when a sad song is playing while you're trying to feel better