Brightness Not working fix

In most of the laptops, the keys provided by the vendor for adjusting brightness seems not working. 

For this you will have to edit your grub file

Step 1 >>> 

Go to location where grub file is located.
/etc/default/grub

you'll have to edit this file but try some thing to edit and save, you will not be able to due to restriction of access. 

Step 2 >>>

You have to give administrator access to the file or location specifically. To do that


First open the terminal and change to root access by entering

:~$sudo su

It'll prompt you to enter password and once you do, you'll gain root access in the terminal.

Then try this code in the terminal

 :~$sudo -R uog+rw /etc/default

This will give any user owner group, access to rear or write in the specific location.

Step 3 >>>

Again go to location where grub file is located.
/etc/default/grub

Locate the line GRUB_CMDLINE_LINUX = ""

Then change it as
GRUB_CMDLINE_LINUX = "quiet splash acpi_osi=Linux acpi_backlight=vendor"

Now you'll be able to save it. Save it as grub in the same location. 

Then go to Terminal again and enter this
sudo update-grub

Now you'll be able to adjust your screen brightness by using the shortcut keys provided by vendor...!!!