Finding out that your crush doesn't like you can be disheartening. I noticed in your other thread that you were considering reaching out to him, is this when you found out he doesn't share your feelings?
What are some things that you do for yourself? Doing things you can enjoy can be a great distraction from negative thoughts. We have a fantastic thread over here that has a huge list of things you can do if you need ideas.
Other things you could try are talking to your support network, is there anyone you'd feel comfortable telling about these feelings?
That situation is really tough. I think in times like these, support from your family and friends can be very helpful. I also think it's important to be kind to yourself. Some people like to do self care activities and dedicate a day to doing something that they enjoy when they find out that their crush doesn't like them back. One thing that helps me when I'm upset about someone is going shopping.