no audio on local news channel

If everything is working except that single channel, then the problem is with the channel, not anything on your end. You can try removing the channel, rebooting the Roku (don't skip this step), then adding it back.

If the audio is still missing, then there's something wrong with either the channel or the feed. Either way, the channel provider would have to fix the issue. 

I am assuming this is a Roku player, and not a Roku TV that you are watching with an antenna and over the air signal.