We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
It's the "Law of Cables", and it's not just Christmas lights. From years of work in electronic labs, I know that cables carefully hung up last night will be horribly tangled today. I am convinced that there is some undiscovered law of physics at work here, but I can't figure it out. Where is today's Einstein when you need him?
The "not working" part is easier to understand. The light strings use cheap plating on the metal electrical contacts. A year of corrosion will result in a lot of the connections failing.
I've had good luck with LED strings where all the parts are soldered. No electrical contacts, no corrosion. Of course, if a LED does burn out, you need a new string, but the bulb type are so hard to repair, it almost amounts to the same thing, and LEDs are many times more reliable