Windows Brightness Control not working
If the Brightness slider is not working on your computer system, then this post will help you troubleshoot & fix the problem. Please go through the entire list and then decide which of the suggestions you would like to try and decide the order you want to try them.
1] Update your Graphics driver
First of all, visit the manufacturer’s website and update your video and graphics drivers, for your model.
2] Restore default settings for the Power Plan
Open Control Panel > All Control Panel Items > Power Options > Edit Plan Settings and restore the default power plan settings by clicking on Restore default settings for this plan. Do this for all your Power Plans.
3] Disable Adaptive Brightness
Disable Adaptive Brightness and see. Open Control Panel > Power Options. Open your active power plan and select Change plan settings option to open the Edit Plan Settings window. Now click Change advanced power settings option to open the Power Options dialog. Next, expand Display and then expand Enable Adaptive Brightness. Set it to Off.
4] Disable the Intel Power Saving Technology
If your laptop used Intel processors, disable the Intel Power Saving Technology. You will get this setting in your Dell or Vaio Control Center. More on this at this Computer screen brightness flickering post.
5] Disable BrightnessReset Task
Open Task Scheduler using Start Search. In the left pane, you will see Task Scheduler Library. Navigate to Microsoft > Windows > Display > Brightness. In the right pane, if you see a scheduled task called BrightnessReset, double-click on it > Properties > Triggers tab > Edit. Now disable it and see if it works for you.
If it does not help, you may re-enable it. Read: No Brightness slider in Windows 11.
6] Run Power Troubleshooter
Run the built-in Power Troubleshooter and see it helps you. You may access it via the Windows Troubleshooters Settings Page or run the following command directly to bring up the built-in Power Troubleshooter Once you hit Enter, you will see the Power Troubleshooter pop-up. Similarly, if you know the Diagnostic Pack ID of any Troubleshooter, you will be able to invoke it using the command line.
7] Use POWERCFG Tool
If you need to further troubleshoot Power Plans, use the built-in PowerCFG command-line tool. All the best! TIP: Windows Monitor Brightness Slider lets you add a Brightness Slider to Windows.