Time service not running

My wife told me that the clock was off by over an hour on her Win8.1
desktop. I brought up the clock setting window (click on the clock). I
set the time correctly, and clicked the box to make it sync with an
Internet time source (the domain name was already filled in).

Then I got a message saying that the Windows time service was not
running, and I should start it. Why in the world would this service
not be running? And how do I start it?

--
Tim Slattery
tim at risingdove dot com