F6

If you accidentally turn off the touchpad and your laptop becomes a Brick there is a way to fix it. I know because I spent an hour with Brick and my backup notebook researching websites and pressing buttons. Brick or PaperWeight, you pick. It was useless. I tried to navigate with the arrows but kept getting stuck. In the end it was simple: Fn and F6. All those little buttons along the top actually do something.

PS: If you accidentally turn off your camera while you're trying to turn on your touchpad its Fn F8. Different on every keyboard, of course. Look at the little icons.