Your domain name is currently pointing to Cloudflare’s nameservers, but Cloudflare does not have any DNS records for your domain. Please set the correct DNS records in Cloudflare or switch your domain name back to our nameservers (which have already been configured correctly for your domain).
Changing your nameservers will not fix the issues with your Cloudflare DNS records, but it will fix your website. To fix the Cloudflare DNS records, you need to fix them yourself. If you have no idea how to do that, then maybe it’s not a good idea to manage your own DNS records?