I have a 2003 panasonic hdtv 1080i, and the picture went completely out. Does it need a bulb replacement?

Hdtv's don't have bulbs, the screens are liquid crystal which is controlled by what is basically a motherboard/cpu. I'd take it in to get looked at but my guess is that repairs won't be cheap.

Do you get audio?

I don't have a plasma, however, if your TV is like the rest of the advanced TVs, maybe you should take a run through the video input ports available to your TV.

It's not uncommon for you to expect a picture on port 1, but inadvertemntly, the TV is now set up on Video 3, which is not connected.

Do you get picture when you select "Setup" on the TV?