In Windows 7, type Control Panel in the search bar, then Appearance and Personalisation, Display and Screen Resolution.
If using the keyboard doesn’t appeal, you can rotate the display in Windows via the control panel. Using the Control Panel to rotate a PC or laptop display Here you can change all your screens (if you're using more than one monitor) to either landscape or portrait. In Windows 7, navigate to 'Appearance and Personalisation', then 'Display and Screen Resolution'. If you don't want to use your keyboard, you can opt for the control panel.