Okay. I listened to all the answers and none actually solved the problem. Here is what I did. I took all of the lights out of the half of the set which didn't work and one by one tested them in the other half of the set (the side that worked). Low and behold, I found 5 of the lights from the side that didn't work would not light. When I plugged them into a socket on the side that worked, the other lights would light up, but the bad one would not. Four of the 5 which didn't light acted that way. But ONE of the lights which wouldn't work was "so dead" that even the other lights wouldn't work. I repeated the test to see if I got the same result and that is what happened.
So, I am now searching for 5 replacement LED lights to see if multiple LED failures caused the problem. I know in regular incandescent christmas light sets, that if too many of the bulbs go out, then the entire set starts to fail quickly. Don't know if the same is true for LED sets.
So... everyone, test the LED lights one by one, find the ones that work and throw out the ones that don't. Find replacement LED lights and plug them in and see if that solves the problem.
These lights came from Holiday Time LED mini light set (50 COUNT) purchased from Walmart.