If using the TV's original feet for standing it up, then the TV should be upside-up since the feet's mounting spots are on the bottom. If using a wall-mount bracket or TV furniture with built-in VESA mount, then do double-check that you didn't mount the TV upside-down
if it a pc output see if someone pulled a prank and set the display up as inverted under the display drivers settings. if it any tv output make sure the tv facing up. if it is try a full system reset on it and the cable box.
If using the TV's original feet for standing it up, then the TV should be upside-up since the feet's mounting spots are on the bottom. If using a wall-mount bracket or TV furniture with built-in VESA mount, then do double-check that you didn't mount the TV upside-down