Sir/Madam,

In an answer to my earlier question you wrote :

1. In Grub press "e" and go to the line starting with "linux" . At the end of "queit splash" append
"acpi_osi=Linux acpi_backlight=vendor " . Press ctlr+X and start the machine. Now check for the brightness
key .
2. Open terminal and install package xbacklight
sudo apt-get install xbacklight
Once it is installed , run "xbacklight -set 50" . If this reduces the brightness of the monitor, then we can map
it with the function key accordingly.
Also send the output of "lspci -vv" and "lshw -html"

----------- I have given the grub content below-----let me know precisely what should I do ---please help--Thanks

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo BOSS`
GRUB_CMDLINE_LINUX_DEFAULT="splash gfxpayload=1024x768x16 quiet"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"