This isn't our first go around. Earth has witnessed extinction events before. However, humans are like cockroaches. There's always a few left that start us on another round of evolution.
World wide events would simply lead to a total breakdown of society and rules a la Mad Max.
I envision the grid going down and lighting the fuse. Survivors will be forced to carry around little balls of flame, because without the internet, they won't know how to start a fire themselves. Mass starvation because they don't know how to forage or hunt. Cannibalism, because that will just be the easiest protein to find. An almost instant rise in communicable disease like cholera, dysentery, plague and others. Eventually, like minded groups will start finding each other. Sharing what knowledge they have individually and the whole ball of wax starts forming again.
Not as well done as AR's scenario, but my meagre contribution anyway.