This problem is usually caused by incorrect, incompatible, outdated, or faulty drivers.
Fortunately, you do not need to reinstall Windows or make other major/complex changes.
This problem is common and often occurs after users upgrade the Windows operating system to Windows 10. If the screen is too bright, it will consume battery power at a faster rate. Some users reported that screen brightness started to change automatically (when it was not supposed to), or the screen brightness control was not working at all. In Windows 10, you can adjust screen brightness settings manually or let Windows do it automatically, depending on whether the computer is plugged in or unplugged. Adjusting screen brightness can also be useful to save batteries (in the case of laptop use). In Windows 10, you can increase or decrease screen brightness depending on the local environment and lighting to make content more visible or comfortable to view.
Can't Adjust Windows 10 Screen Brightness, Windows 10 Brightness Control Is not Working.
