my website is not working
Welcome to the Cloudflare Community!
A bit more information than that is needed. What’s not working? What is the exact error you get (screenshot helpful), and what is your website/the URL with the issue?
That HTTP 500 Error is being returned by your origin, the web server behind Cloudflare. The response headers have x-powered-by PHP/7.2.7 & ASP.NET, if that helps you know where better to look.
You can check out the community tip about 500 errors as well:
Community Tip - Fixing Error 500: Internal Server Error
I would start by reviewing any application logs you have. If you are using managed hosting, reach out to your hosting provider for more help.