I have a 4 year old RCS rear projection HD TV. Last night everything was fine- this morning no picture, sound is good. I tried a DVD and it played. Could this be the satellite?

By playing a DVD, you've shown that most of the circuits and the lamp is OK. It's *possible* that the input that is connected to wherever you get your live TV (satellite receiver?) is bad, but that would be unlikely in my opinion.

Yes, it could be your satellite receiver.