This is not unusual for Windows, so, you can fix this issue by restarting your computer.
Check every part of hardware to resolve this issue. Take a look at these possible reasons why the light is not working on your system OS:.
Why is the Asus keyboard backlight not working?
To keep decreasing the backlight until it gets turned off, hold the F3 and Fn keys.
If you hold these two keys together, the brightness of the backlight will increase. All you need to do is press the F4 and Fn keys at the same time.
