Why has my sound stopped working

Why has my sound stopped working

I have Dish Network Satellite TV. I was watching a movie yesterday and suddenly there was no audio. i tried to re-boot the Dish but no improvement. I switched the dish input to another HDMI port and still no audio on any channel. I switched out the Vizio for another TV and audio works fine. So pretty sure there is a problem with the Vizio audio. What now?

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