edit note: don't change anything related to intel files especially
because yours is NVIDIA and it broke my Ubuntu. I couldn't open Ubuntu anymore, so I removed 20-intel in safe mode from the console.
JUST do this to recreate:
this will recreate etc/X11/xorgconf
be root then execute this on terminal
lastly be sure that you are pasting
enablebrightness in right section which is section "device"
for nvidia and ubuntu 14.04 x64
check this post ... it solved mine.
ubuntu 14.04 fn brightness nvidia not working samsung r540
HOW I SOLVED IT
this creates /etc/X11/xorg.conf . edit it.
# sudo su // become root
# gedit /etc/X11/xorg.conf
find Section "device" in text.
it should look like this on the right side:
from this TO this
Section "Device" | Section "Device"
Identifier "Device0" | Identifier "Device0"
Driver "nvidia" | Driver "nvidia"
VendorName "NVIDIA Corporation" | VendorName "NVIDIA Corporation"
| <strong>Option "RegistryDwords" "EnableBrightnessControl=1"</strong>
EndSection | EndSection
save changes (ctrl+S).
log out. log in.
we are done!!
now Fn + Up/Down is adjusting the brightness.
this post will make your fn+up ,down keys work