LAMPP Won’t Start, Web Server Already Running

What I did:

$sudo /opt/lampp/lampp start
Output :
XAMPP: Starting Apache…fail.
XAMPP: Another web server is already running.
XAMPP: Starting MySQL…ok.
XAMPP: Starting ProFTPD…ok.

How I solved it:

exsudo /etc/init.d/apache2 status
sudo /etc/init.d/apache2 stop