Restore Asus Laptop to factory settings

I have ASUS F555L laptop and I would like to recovery all the system. Unfortunately, when I restart the computer, I press F9 and nothing happen. how can I do? is there another way to re-install the system? I tried to press F9 immediately after the start or after the logo ASUS appears but F9 doesn't work. I tried another key, for instance F2 and that's working.