For whatever reason, you took a photo that is not oriented correctly. Some high end digital cameras can make adjustments for you, however many take photos that are badly oriented and do not realize it at the time they take the picture. SILKYPIX has excellent tools for Perspective Correction.
The Rotation Tool lets you adjust the angle of the photo without losing any pixel content.
The digital shift corrects an the effect that one would normally achieve through using with a tilt and shift lens. When you photograph a building with a wide-angle lens, the original perspective is lost. The Shift sliders corrects the perspective and will display the original object with straight horizontal & vertical lines.
When you photograph a person from a higher position, it appears their the legs and feet are shortened.