Ok, went through all the selections on input again on my tv remote and the only one that works is the HD 3 because I have it hooked up to that one. It is also the only selection where the roku box noise comes on when I press the roku keys. So this must be the right place, but still no screen, just black screen . What do I need to do to find the picture here? Is there some setting which I don't know about which should be working here? Thanks.
It may be time for some serious troubleshooting. You'll want to ensure you have the original TV remote (it seems you have that) and the Roku remote. And, I'm reading that you've connected the Roku to the TV via HDMI 3 via an HDMI cable only.
First, let's rule out an issue with HDMI 3. I'll assume you have at least two other HDMI inputs on your TV. Pick one. Say, HDMI 2. Power everything down and disconnect the current HDMI device from HDMI 2. Then, connect the Roku to HDMI 2. Power up the Roku, then turn on your TV, switching the input to HDMI 2. What works? Sound? Picture?
If no image, there may be a problem with the Roku, since that would mean sound but no picture on two separate inputs.