There's a whole science fiction series by author S. M. Sterling, SwoLy, that deals with exactly that, and it's very good. Here's the first novel: Suddenly, there's no electricity. Jumbo jets fall out of the sky, cars quit running, lights don't work, you name it... if electricity is involved, you're screwed. Suddenly, the Middle Ages is upon us. People die in droves. Refrigeration doesn't work. When the canned food starts to run out, the people in the cities begin to starve. Getting clean water becomes difficult. It's a trip to read. CometsWin will enjoy it because some people become warlords.
The first few episodes struggle if you take them individually. The season got better as it went along. There are a few characters that are decent. Once the writers figure that out they will do a better job sort of like with LOST.
