When I upgraded the OS to Windows 10 on an Asus laptop, I lost the ability to disable the touchpad with the fn + f9 keys. I searched online for a way to help with this problem but with no success. Hopefully, this helps anyone with a similar situation.
Step 1: Open Task Manager
Open your task manager, ctrl + alt + del, or by searching for it.
Step 2: Select Startup Options
Select the startup tab.
Step 3: Disable ETD Control Center
If you don’t immediately see the ETD Control Center, you can sort programs by their status.
Please turn it off by right-clicking or pressing the button in the bottom right corner.