Apache2 enable / disable sites & modules
Enable site (virtual host)
sudo a2ensite [filename.conf]
Disable site
sudo a2dissite [filename.conf]
Enable an apache2 module
sudo a2enmod [module_name]
Disable an apache2 module
sudo a2dismod [module_name]
Force reload the server
sudo /etc/init.d/apache2 force-reload
OR
sudo service apache2 reload