Thanks for joining the NUC community.
It appears to be an issue with the sound playback set to the wrong device, please check the following URL for troubleshooting assistance:
Hi, Thanks for the reply, I will bookmark your URL.
The sound is back now. Windows 8.1 - In the control panel I set the sound to 100, no joy. I took the curse to bottom right hand corner and brought out settings. In settings there was a sound icon and when clicked I found that the sound level was zero. Nudged it up and now have sound. No clue as to how it got to zero and or why it never caused problems previously.