View, Open or Close Recently Used Apps - Windows 8
Viewing recently used apps is only available from the Start or Apps screen.
From the left edge of the Start or Apps screen, swipe right then, prior to lifting your finger, swipe left to display the recently used apps menu (apps are displayed on the left).
To navigate to the Start screen, tap the Start icon (located on the right edge of the screen).
If using a mouse, move the pointer to the upper-left corner of the Start screen, wait until a thumbnail of an app appears, then move the pointer down the edge of the screen to open up the list.