Installing memcached on my laptop has really been a pain till now. Nothing seems to work as expected. Although memcached is installed , which i see by testing it on the console, it doesn't show up in  phpinfo()  .

While installing memcached , i changed some defaults( unintentionally) , which included apache to run on system startup, so lampp would not start. Here is the solution

when debian7 start,it will start apache2. so you should stop it first,than try to start lampp.

/etc/init.d/apache2 stop
/opt/lampp/lampp restart


This is however a one time solution. No worries!! 

Change the defaults, use this:(ubuntu >11.04)


echo "manual" >> /etc/init/mysql.override
update-rc.d -f apache2 remove


Will update this post when memcached is installed!!


UPDATE!!

After numerous attempts at installing memcached, i uninstalled lampp and installed it again, I didn't uninstall memcached however, and somehow when i restarted wamp, I could see memcached in the phpinfo() !!

This might not work in every situation, but it offers a possibility in case all other methods fail.