This article explains how to wake up a computer that is in sleep mode, and what to do if the normal methods don't work.
How to Wake Your Computer from Sleep Mode Using the Keyboard
Regardless of which operating system you are using, you can easily turn off sleep mode by turning the computer back on. You do this by interacting with it in some way.
Usually this means one of the following:
With some devices it is a little different and they only respond when you press the power button or a dedicated sleep button.
