it is usually the fn + f9 key to fix it...
i made the mistake last time of pressing the fn + f9 too many times and there was a lot of "static energy build up in the motherboard..."
I called the Asus support and this is how they fixed it
first they had me shut the laptop all the way down
then I held the power off button for thirty seconds(to remove static energy from motherboard)
then I turned laptop on again by pressing powerbutton
it took me to a blue screen
I was advised to press f9 key(optimized defaults) and press yes
then I was advised to press f10 to save configuration and press yes
then the laptop started back up
my touchpad still wasn't working but I was advised to press the fn button down and then tap f9 key one more time and... voila!!
hopefully that helps