edit note: dont change anyting realted to intel files especially usr/share/x11/20-intel
cuz your is NVİDİA and it broke my ubunut could open ubuntu anymore.so in safe mode i removed 20-intel from console
JUST do tihs to recreate.
this will recrate etc/X11/xorgconf
be root then exectute this on terminal
lastly be sure that you are pasting enablebrigtnes in right section which is section "device "
for nvidia and ubuntu 14.04 x64
check this post ... i 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 shold look like it on the rightside
from this TO this
Section "Device" | Section "Device"
Identifier "Device0" | Identifier "Device0"
Driver "nvidia" | Driver "nvidia"
VendorName "NVIDIA Corporation" | VendorName "NVIDIA Corporation"
| Option "RegistryDwords" "EnableBrightnessControl=1"
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