I believe what farmerman was getting at had nothing to do with tipping the TV over - I think he was referring to what is called a "Hard Reset", accomplished through an extended period (several minutes at least, overnight is generally good) of the unit being disconnected from mains power - unplugged. Often, this will cause the unit to clear all previously user-defined settings, re-initialize and present its setup menu when next powered up and turned on.
From what you've said so far, it seems to me there is no other explanation than a display settings issue; something, overwhelmingly likely available through the set's menu, is affecting the display. I suggest again you locate and consult the set's user guide/owner's manual, which, if you don't have a hard copy, should be available through the set vendor's website support pages, and even if not, should be something you can order from the vendor.
When all else fails, R
anual - always a good place to start