LAMPP does not work quite like standard LAMP stacks.
please try starting LAMPP with this command (as root)
/opt/lampp/lampp start
See if LAMPP starts ok, please...
Was LAMPP stopped when you issued that command??? or were you trying to 'start Apache'????
LAMPP is run by a bash script (/opt/lampp/lampp), with a set of delimited options (arguments) that are invoked by that script. What I am saying is you may not be able to use some Apache CLI options.
The arguments are outlined in the LAMPP FAQ's -
http://www.apachefriends.org/en/xampp-linux.html(down toward the bottom)
You can also open the bash script (/opt/lampp/lampp) with an editor - look around line 128 for the arguments available (cases)
Good Luck