Answer by cioby23 for Lubuntu 14.04 - Disable screen saver....for real this time?

In order to disable the scren blacking use the following two commands in the .xinitrc file before any existing exec startlxde command:

xset s off &xset -dpms &

If you do not have this file please create it in your home directory and paste the above content:

touch ~/.xinitrc

Make sure it is an executable script, by running

chmod +x ~/.xinitrc