Have you tried the FN + F4 key combo?
Here are some troubleshooting steps that may help.
- Do start by uninstalling/reinstalling the keyboard driver.
- Go to Device Manager and uninstall the keyboard driver then reboot your laptop.
- Observe after the reboot and see if the same problem will persist.
- If that doesn't work, do try installing this ATK driver for your keyboard
Go to https

/www.asus.com/support/Download-Center/ and search for your model to get the driver.
- Once installed, reboot your laptop.
- If all these will not work that means it's a hardware problem and replacing the keyboard will be the last resort.