screen brigtness doesnt work

i cant change the my brigtness level in ubuntu 14.04. i tried so many time. and my backlight folder is empty also..

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-4.2.0-35-generic 4.2.0-35.40~14.04.1 [modified: boot/vmlinuz-4.2.0-35-generic]
ProcVersionSignature: Ubuntu 4.2.0-35.40~14.04.1-generic 4.2.8-ckt5
Uname: Linux 4.2.0-35-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Aug 1 21:09:49 2020
InstallationDate: Installed on 2020-08-01 (0 days ago)
InstallationMedia: Ubuntu 14.04.4 LTS "Trusty Tahr" - Release amd64 (20160217.1)
SourcePackage: linux-lts-wily
UpgradeStatus: No upgrade log present (probably fresh install)