I changed the channel on the remote, I can't get it back now (Viera)

I changed the channel on the remote, I can't get it back now (Viera)

I mistakenly hit the up arrow (channel button) on my remote. That changed the channel to where it won't connect. I don't have cable, I use a Roku. I'm not sure of the term there, auxiliary? I scrolled up and down through 120+ channels - no luck. What's the next step?

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