Windows 8.1 and Windows RT 8.1
use power efficiently, so you won't need to shut down your PC unless you're going on vacation or will be away from your PC for a while. However, you’ll occasionally have to restart your PC after you’ve installed a new app or to finish installing updates. Here's how to do it.
Before you restart, save your work and close any apps you have open.
Swipe in from the right edge of the screen, and then tap Settings.(If you're using a mouse, point to the lower-right corner of the screen, move the mouse pointer up, and then click Settings.)
Tap or click Power, and then tap or click Restart.