Turn the tv on its axis to see how much the earths magnetic field
affects the tilt.

There is no adjustment for tilt on any current 27" or smaller tv set,
some 32" sets and larger have a user menu tilt correction.

Odds are that you simply have the tv turned and the earths magnetic
field is affecting the tilt you are seeing. The specifications are
depending on where you live, but in most of the midwest the magnetic
field only tilts the image as much as about 3/8" across the bottom or
top of the screen.