Can't get backlight to work on keyboard

The HP 255 G9 does not include a backlit keyboard in every configuration, so first use the notebook’s exact product number—not only “HP 255 G9”—to verify whether your unit contains the backlit-keyboard hardware.^1^

Check the exact configuration

1. Find the product number on the notebook’s label or packaging. It should be more specific than the model family name.
2. Open HP’s model-specific specifications page and search using that product number.^2^
3. Look under the keyboard or input-device specifications:
   • If it explicitly says backlit keyboard, the hardware is installed.
   • If it lists only a standard, full-size, or spill-resistant keyboard without “backlit,” there is no light to enable through Windows.

The absence of a control under Settings > Personalization is not evidence of a Windows fault. Windows Dynamic Lighting only displays compatible lighting devices; it cannot add backlighting to a keyboard that lacks the necessary LEDs and controller.^3^

If HP confirms that your configuration is backlit

Since you have already tested the function-key combinations, do not keep repeating them. Proceed with these checks:

1. Restart and test before Windows loads.
   Enter the HP startup or firmware screen and test the keyboard-light key there. If it never illuminates outside Windows, contact HP because that points away from a Windows personalization setting.
2. Reinstall the keyboard device in Windows:
   • Right-click Start and select Device Manager.
   • Expand Keyboards.
   • Right-click each built-in keyboard entry and select Uninstall device.
   • Restart the notebook; Windows should reinstall the devices automatically.
   Reinstalling the keyboard device is a general fallback for a backlight that should be present but no longer responds.^4^
3. Install the HP-specific firmware and hotkey software offered for your exact product number through HP’s support tools. The backlight shortcut is a hardware/firmware function rather than a normal Windows Fn-key setting.^5^

If HP’s specification confirms a backlit keyboard but it still does not illuminate before Windows starts, the appropriate next step is HP hardware support or warranty service.

References

1. HP 255 15.6 inch G9 Notebook PC specifications | HP® Support
2. HP 255 15.6 inch G9 Notebook PC (785Z0AV) - Specifications ...
3. Control Dynamic Lighting Devices in Windows | Microsoft Support
4. Backlit of keyboard not working - Microsoft Q&A
5. FN lock will not turn off despite every solution - Microsoft Q&A