one channel without sound

I had the same problem only it was no sound on Channel 7.  All other channels worked fine.  After trying to reinstall mini box and remote several times I returned both and got a new set.  New mini box and remote work fine.  No other issues.  No way of knowing which item was bad but issue resolved by replacing both.  Good luck.

appreciate your response.  I was chatting with online help at cox and their final answer was that it will usually resolve itself within 24 hours.  maybe not the best answer for a customer 

When there is no sound, if you switch to secondary audio (SAP) is there sound then? Also, does it happen on all TV's at the same time? If it went away, disregard. 

I have exactly the same issue. Fox News channel has no sound at all.  Never has the entire time we've been subscribed (9 months) so it's not going to resolve itself in 24 hours.  Additionally, I turned Fox on this morning to read the crawl.  When it went to commercial, a Cox advertisement came on, and SO DID THE SOUND!!!!  As soon as the Cox ad was over, all sound was lost again.  A little too coincidental.