Well, there's movies/books where a totalitarian/dystopian government/entity controls everything, such as 1984, Brave new World, V for Vendetta, Brazil, Logan's Run, Fahrenheit 451, Children of Men, Equilibrium, THX 1137, Zardoz, Metropolis etc ....
Then there's ones where anarchy rules, Road Warrior, etc ...
Then there's the disaster/postnuclear war movies/books ... "The Day After" (which was a heaping pile of crap from the 80s) depicted a post nuclear war USA, it was pretty torn down and miserable .... Planet of the Apes movies, etc ...
And then there's ones where zombies take over the world and kill just about everyone, Night of the Living Dead, 28 Days Later, Dawn of the dead, The Omega Man, The Last Man on Earth, etc ...
I would say the absolute most torn down and desperate world of any that I've ever seen would be the Planet of the Apes series. Mankind is pretty much reduced to incompetent slaves or fvcked up cult members who worship a nuclear bomb.
I also think Last Man on Earth/The Omega Man/I Am Legend deserve a mention. The versions with Heston and Prices were darker than the Smith version, but all show pretty much hopelessness for humanity.