Hello Linux Geeksters.
If you also get the problem of no backlight in Ubuntu 13.04 after resuming from suspend or sleep, this
is what you have to do to fix it:
Open /etc/pm/sleep.d/00-diplayfix in a text editor and paste the following script:
$ gksudo gedit /etc/pm/sleep.d/00-displayfix
case "$1" in
echo 500 > /sys/class/backlight/intel_backlight/brightness
Set executable permissions on /etc/pm/sleep.d/00-displayfix:
$ sudo chmod +x /etc/pm/sleep.d/00-displayfix
This should fix your backlight problem on Ubuntu 13.04.