Affects Systems with Intel based graphics

This can be a common occurrence on systems with Intel graphics built-in which often have hot-keys which can rotate the display (useful if you have a monitor that rotates to the portrait position).

So if you find yourself facing a screen which has been rotated 90 degrees left or right or even upside down, do not fear and certainly don't strain your neck!  You simply need to press the hot-key to set it back in the upright position.

Ctrl + Shift + Up Arrow  -- gets you to the 0 degree (upright) position.

Ctrl + Shift + Left Arrow -- gets you to the 270 degree (or left) position.

Ctrl + Shift + Right Arrow -- gets you to the 90 degree (or right) position.

Ctrl + Shift + Down Arrow -- gets you to the 180 degree (or upside down) position.

On some systems, you may find an Intel graphics properties icon in the system tray area which will also describe these hot-keys, but the hot-keys may work nonetheless.