We apologize to hear about the audio issue with your Roku TV. We understand your sentiments regarding this and we would feel the same way. We will work with you to know what went wrong so we can assist you further and fix the issue.
Here are a few things to try:
Customers have reported that unplugging their Roku TV for 5-10 minutes and then plugging the Roku TV back in resolves the issue.
if the issue only happens on one channel, remove the channel and then, restart your device. Once it loads up again, add the channel back once more and try playing content again. You can visit this Support article for detailed instructions on how to do it: How to resolve a channel playback issue | Official Roku Support
This should resolve the issue you are experiencing, however, if the issue is still unresolved, please reply back and we will be able to assist you further.