Are you sure that you have a soundbar and not a streambar?
What you are describing sounds like you added a streambar, which is a soundbar with a built-in Roku. If you then changed to the input where the streambar is connected, it would look much like the Roku TV interface, but it would be missing the TV-specific parts like the local/over-the-air TV channels. If so, to get back, you would pick up the TV remote and change the input back to the antenna.
I suspect a Roku steambar or player connected to a Roku TV can be confusing until you pick up on details.
