Check whether your keyboard has a backlight feature
Look for a backlight key, often on the F keys or spacebar area
Press the backlight key
Hold Fn and press the backlight key if needed
Use the keyboard settings in your device’s control panel or settings app
Adjust keyboard brightness if available
On a laptop, make sure the keyboard backlight is enabled in BIOS or UEFI if the key does not work
On a desktop, check the keyboard software or driver settings
If it still does not turn on, consult the device manual or manufacturer support