Panasonic television model # th-50px60u . I have a strange looking square in the upper right corner of the screen. It Is not cc or pip. Have the same rainbow looking 12in x 12in square even when I play a dvd. Please ! I need help

This sounds like a driver board on the display has gone out. There are several of them around the edges of your screen (in back) that drive the display. Each one is responsible for a section of the display. They CAN be replaced, but I don't know the cost as mine went out the week before the warranty was up (luckily!).

Good luck,
WallyH