I can hear audio but the screen on my tv is black with rainbow?

When I turn on my tv I have perfect audio but the screen is black with a rainbow through the middle that flips around and sometimes shows the picture thats on tv but then flips back out. Sometimes it looks like the picture is at a 45 degree angle away from the actual screen. Can this be fixed or is it done. It is a 54 inch Sony self standing model with the plastic type screen. May be called rear projector, not sure. thanks