Check whether your keyboard has a backlight key or shortcut
Press the backlight key, often marked with a keyboard light icon
Try the Fn key plus the backlight key
Use the keyboard brightness keys if available
Open your device keyboard settings and enable keyboard backlight
Increase the backlight brightness in settings
Restart the device if the backlight does not turn on
Update keyboard or system drivers if needed
Check the user manual for the exact shortcut for your model