the brightness function isn't working in my pc what do i do about it . i already tried everythind the brightness bar is moving on its panel but i'm unable to adjust the brightness

If the brightness slider moves but the screen brightness does not actually change, the most common causes are the display driver, monitor type, or automatic/adaptive brightness behavior.

1. Check whether this is an external monitor.
   • If the PC is connected to an external monitor, Windows might not show or control brightness for that display.
   • In that case, use the physical brightness buttons on the monitor itself.
2. Try changing brightness from Settings.
   • Go to Start > Settings > System > Display.
   • Under Brightness, adjust the slider.
   • On Windows 11, brightness can also be changed from the Network icon area on the right side of the taskbar.
3. Turn off content-based adaptive brightness.
   • Go to Start > Settings > System > Display.
   • Select Brightness.
   • Set Change brightness based on content to Off.
   • This stops Windows from automatically changing brightness and contrast based on what is on the screen.
4. If automatic brightness is enabled, test by turning it off and back on.
   • Go to Start > Settings > System > Display.
   • Under Brightness, check whether brightness automatically when lighting changes is available.
   • Toggle it off, then on again.
5. Update the display driver.
   • Open Device Manager.
   • Expand Display adapters.
   • Right-click the display adapter and select Update driver.
   • If the brightness slider is missing or does not work, Microsoft recommends updating the display driver.
6. Check Windows Update optional driver updates.
   • Go to Settings > Windows Update > Advanced options > Optional updates.
   • Install any available display-related updates, then restart.
7. If Device Manager shows Microsoft Basic Display Adapter, install the correct graphics driver from the PC or laptop manufacturer.
   • That usually means the proper graphics driver is not installed or is corrupted.
   • After installing the correct driver, restart and test brightness again.
8. If auto-brightness stopped working after a recent Windows update on Windows 11 24H2 or 25H2, use the temporary workaround.
   • Adjust the brightness slider manually once, or press a brightness hotkey.
   • Plug or unplug the charger.
   • Turn Battery Saver on or off.
   • Put the device to sleep while on battery power.
   • These actions can reactivate the ambient light sensor.

If this is a desktop PC with an external display, the expected result is that Windows brightness control may not work at all, and the monitor’s own controls must be used. If this is a laptop with a built-in display, focus first on the display driver and optional updates.

• Change the brightness, contrast, or sharpness of a picture | Microsoft Support
• [Windows 10](https://support.microsoft.com/windows/hardware/display-graphics/change-display-brightness-and-color-in-windows#adjust-display-brightness)
• [Windows 11](https://support.microsoft.com/windows/hardware/display-graphics/change-display-brightness-and-color-in-windows)
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