I have a philips big screen TV and all of a sudden the colors on the TV seem to have a yellow shadow. What caused this and is there anyway to fix it

Few questions:
Is this a Plasma or LCD flat screen TV?
Is the yellow over the whole of the screen?
Has the screen been dropped or knocked since this yellow shadow appeared?
Has the TV been moved by a magnetic source like speakers from a stereo?

There is a red light bulb and red key and TV keeps shutting off