you need to download keyboard light driver and re-install the corresponding driver:
Step 2: If you encounter keyboard backlight not working after windows 10 update, this may be due to damage to the related system files or drivers. If you still won't turn on the keyboard backlight, continue to the step 2 Normally, the switch of the backlit keyboard will have alight-emitting icon on the keyboard key, and the switch of the backlit keyboard light can be controlled by combining the FN. Step 1: Try pressing 'FN + Space' to turn keyboard backlight on or off (keyboard backlight shortcuts depend on the keyboard model). Steps for How to Repair Keyboard Backlight Stop working
Therefore, several solutions will be listed in this article, hoping to solve this problem. “Why is there no backlight on my laptop keyboard?” I saw a problem like this on some forums.
