Cloudflare offers a number of layers of protection from malicious attacks and also helps with increasing website performance. If you are managing your domains on Cloudflare through cPanel using providers such as Justhost or hostgator, you might encounter a situation where enabling or disabling Cloudflare will cause your site to go offline. Here are some steps you should take to get your site back online ASAP.
Login to your server using SSH as root
Check whether httpd service is running service httpd status
If not running, attempt to restart httpd service service httpd restart
If it fails, you will get an error regarding Cloudflare config file. Using vim or nano, edit /etc/apache2/conf.d/includes/pre_main_global.conf and comment out or remove this line /etc/httpd/conf.d/cloudflare.conf