By taking the plug out and putting it back in solved the problem. All sound settings in windows 8.1 were set to default, as were all the settings in the dell audio program that was factory installed.

Haven't touched bios or anything else in years. Went to settings. went through the whole sound/speaker pages. No sound when configure testing. Ran trouble shooter and now have sound in configure ...

Dell's XPS 27 7760 all-in-one desktop PC has a gorgeous 4K IPS touch display and a 10 speaker sound system that delivers bang for your buck in more - Page 2 ...