Some Windows 10 users have reported that their screen brightness changes automatically or does not work properly. If Windows 10 Brightness is not working or changes automatically 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.
Windows 10 Brightness not working
1] First of all visit the manufacturer’s website and update your video and graphic drivers, for your model.
2] 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 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] 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 Laptop screen brightness flickering post.
5] 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.
6] Run the built-in Power Troubleshooter and see it helps you. You may access it via the Windows 10 Troubleshooters Settings Page or run the following command directly to bring up the built-in Power Troubleshooter
msdt.exe /id PowerDiagnostic
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] If you need to further troubleshoot Power Plans, use the built-in PowerCFG command line tool.
All the best!