The solution depends on the computer's operating system. For example, on a Windows 8 touchscreen laptop, swipe from the right edge of the screen, click Settings, select Power, and then choose Restart. In Windows 7, click the Start button, then the arrow next to Shut Down, and then Restart.
In Windows the Restart command completely resets a PC, but with Macs, Restart only refreshes the computer's memory; turning it off and on fully resets it. Therefore, if you don't need to fully reset your Mac, click the Apple button on the menu bar, then choose Restart. You can also press Control+Command+Eject (or Control+Command+Power) at the same time; either keystroke combination acts as the Restart command.