For a laptop, a greyed-out brightness control usually points to the display driver not working correctly or not being recognized by Windows.
Try these steps in order:
- Check whether the device is using the built-in display
- Windows brightness controls are mainly for the laptop’s internal screen.
- If an external monitor is connected, the brightness slider might not appear or might not work. In that case, adjust brightness using the monitor’s own buttons.
- Update the display driver in Device Manager
- In the taskbar search box, type Device Manager and open it.
- Expand Display adapters.
- Right-click the display adapter name and select Update driver.
- Follow the prompts, then restart the laptop.
- Reinstall the graphics driver from the laptop manufacturer
- If the problem started after an update, reinstall the graphics driver recommended for the exact laptop model from the manufacturer’s support page rather than only updating it.
- This is a common fix when the brightness control becomes greyed out after a Windows update.
- Check Display settings
- Go to Settings > System > Display.
- If the brightness slider is still missing or disabled after the driver is corrected, Windows is still not detecting the display path properly.
- If automatic brightness is involved
- Go to Settings > System > Display > Brightness.
- If supported, turn brightness automatically when lighting changes on or off.
- On some Windows 11 24H2 and 25H2 systems, auto-brightness can stop responding until another brightness-related action occurs. A temporary workaround is to manually move the brightness slider, press a brightness hotkey, plug or unplug power, toggle Battery Saver, or put the device to sleep while on battery.
If the laptop brightness slider is greyed out, the most direct fix is usually to reinstall the laptop maker’s recommended graphics driver.