There's many reasons why you might not be able to sleep, but I'll try and focus on your body in this. I want you to relax your facial muscles, your jaw, your eyes... exhale, relax your chest, too. Drop your shoulders, I know a lot of tension can also be held there and you might not have realized it. And make sure you aren't too hot or cold and you aren't hungry/thirsty!
Do you have everything you need to sleep with? Double check that you have any stuffed animals or blankets you might be missing. I'm not sure if this is a huge problem for you, but keep your eyes off any clocks. Watching the time pass is only more likely to keep you up!
I hope that helps somewhat. Normally I'd encourage you to talk to me but I would hate to keep you up... but if you really need to text me, go right ahead. I would never mind. So, now that you're done reading this, I want you to turn off your device, tuck yourself in, and keep trying your best to relax. I believe in you! Have a good night and a wonderful rest my dear. May you feel refreshed in the morning. :)