Black section on m vizio screen

Question

hi. last night when watching tv a black, square section appeared in the bottom right hand corner.at first i thought it was part of the skit then realized it wasn't going away.turned it off and back on no change. turned it off for the night and still the same today.my gf is coming home thursday....i didn't do anything to it but it would be great if i could do something to fix it. help please. eeks.