brightness problem

[PARTHEEP]

brightness is not working.not able to change it at all thus reducing battery please help me out with the issue

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xorg 1:7.7+1ubuntu8.1
ProcVersionSignature: Ubuntu 4.2.0-34.39~14.04.1-generic 4.2.8-ckt4
Uname: Linux 4.2.0-34-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Mon Apr 4 13:43:39 2016
DistUpgraded: Fresh install
DistroCodename: trusty
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.7, 4.2.0-30-generic, x86_64: installed
 bbswitch, 0.7, 4.2.0-34-generic, x86_64: installed
GraphicsCard:
 NVIDIA Corporation GF119M [GeForce 410M] [10de:1055] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Sony Corporation Device [104d:908b]
InstallationDate: Installed on 2016-02-27 (37 days ago)
InstallationMedia: Ubuntu 14.04.4 LTS "Trusty Tahr" - Release amd64 (20160217.1)
MachineType: Sony Corporation VPCEH3AEN
ProcEnviron:
 LANGUAGE=en_IN:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_IN
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-34-generic root=UUID=a4a95f37-4ebb-47ad-af12-87c9aa592df7 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/19/2012
dmi.bios.vendor: INSYDE
dmi.bios.version: R0200Z9
dmi.board.asset.tag: N/A
dmi.board.name: VAIO
dmi.board.vendor: Sony Corporation
dmi.board.version: N/A
dmi.chassis.asset.tag: N/A
dmi.chassis.type: 10
dmi.chassis.vendor: Sony Corporation
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnINSYDE:bvrR0200Z9:bd04/19/2012:svnSonyCorporation:pnVPCEH3AEN:pvrC106Z5V1:rvnSonyCorporation:rnVAIO:rvrN/A:cvnSonyCorporation:ct10:cvrN/A:
dmi.product.name: VPCEH3AEN
dmi.product.version: C106Z5V1
dmi.sys.vendor: Sony Corporation
version.compiz: compiz 1:0.9.11.3+14.04.20150313-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.64-1~ubuntu14.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri N/A
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A
xserver.bootTime: Mon Apr 4 13:16:09 2016
xserver.configfile: default
xserver.errors:
 Failed to load module "nvidia" (module does not exist, 0)
 Failed to load module "nvidia" (module does not exist, 0)
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.17.2-1ubuntu9.1~trusty1
xserver.video_driver: nouveau