Could be a lot of things. Before taking it to a shop, I would check some basic stuff. First, make sure all of the cables are plugged in good and tight. I would even recommend using a different cable type to see where the problem is. If you use component cables now, try composite or S-Video, or whatever way you aren't trying now. Also, did all of the inputs go bad? Can you plug a DVD player of something into another input and get it to work? It is possible that you lost the red and blue guns first and then the green one died, but that seems fishy, because there would have been something that triggered them all to go bad. No matter what you find, I doubt that you'll be able to fix it yourself. I have a Hitachi where the entire input board went bad, but there was nothing wrong with the rest of the TV. Luckily, I know people in the TV repair business and was able to get a replacement board and fix it myself. If you don't know much about TVs, just do some basic testing and get it to a repair shop. You don't want to make it worse by opening it up and tinkering yourself. Hope this helps... ---NEW SECTION--- Based on your comment, it sound very similar to the problem I had with the input board itself. I would call a repairman, because you have probably gone as far as you can. If you are gutsy (meaning, don't blame me if you break anything), you can open the back and find where the input board connects to the main board. It will probably look something like a sound card/video card connection in a PC. You know, where the riser card goes into slots on the main board... You might try pulling it out (make sure everything is unplugged and has been for 30 minutes!). Use a can of Air Duster to clean the input board and the slot it plugs into and plug it back in. If you are lucky, this might fix it. Again, I have never personally worked on Toshibas, so I can't be sure of the connections. If you see anything that you don't understand, don't mess with it.