Click the icon in the upper left corner of the title bar and select Restore,
Or click the 
button,
Or right-click the window title bar and then click Restore,
Or press ALT+SPACEBAR+R (application) / ALT+HYPHEN+R (document).
Restores the active application window or document window to the size and location before the Control Maximize or the Control Minimize command was used.
To restore the window:
Click the icon in the upper left corner of the title bar and select Restore,
Or click the button,
Or right-click the window title bar and then click Restore,
Or press ALT+SPACEBAR+R (application) / ALT+HYPHEN+R (document).