This key is usually one of the function keys (F1, F2, etc.) and may have an icon that looks like a keyboard or light. 3. Press and hold the "Fn" key and then press the key with the keyboard light icon. This should activate the keyboard light on your laptop. In addition, some brands of computers are turned on by pressing win+spacebar. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.