Restore backlight on Ubuntu ?

Using Ubuntu as main OS for years now on all Laptop and desk
top at home, I am regularly in front of common problems. But one of the most anoying is the « backlight off bug »,

Samsung-q210

Sometimes, after kernel update, my laptop LCD decide to stay off, for unknown reason.

So only one way to restore it:

sudo vbetools dpms on

This is the only solution I have found to restore the « ON » state.

After any reboot, the LCD stay ON.

Ubuntu is sometimes frustrating for newbies. So here is ONE solution.

Have Fun(buntu ?)