There are hundreds of novels about the apocalypse, here are just a few that I have enjoyed...
Non-stop (1958) by Brian Aldiss. Aftermath of collapse of society in a generation star-ship. You might also try
Greybeard (1964), a story of a future where everyone is sterile and the youngest couple left in the world are in their 50's, or
Hothouse (1967) a story set after the virtual exinction of humanity where the survivors compete (poorly) with other animals in a world-girdling jungle.
A Canticle for Leibowitz (1959) by Walter M Miller (won the Hugo) a story of rebuilding civilization after nuclear war.
The Forge of God (1987) by Greg Bear, an end-of-the-world story - don't trust aliens (it also has a sequel,
Anvil of Stars).
Wolf and Iron (1990) by Gordon R Dickson, a detailed and gritty story of survival after society collapses in the USA.
Death of Grass (1956) by John Christopher, a plague has wiped out all grasses and cereals. Civilization is proved to be a thin veneer when people must fight to secure what little food remains.
Day of the Triffids (1951) by John Wyndham, when the population of the world is blinded, genetically-engineered mobile plants find themselves accidently in the ascendency.
The Chrysalids (1955) by John Wyndham, in an agrarian world recovering from nuclear war, mutant children try to hide their telepathic powers from a society that will kill them without mercy - a hint of Salem perhaps?
Farnham's Freehold (1964) by Robert Heinlein, an American family are catapulted into a post-nuclear society that highlights the assumptions and prejudices of 1950's America by inverting them.
Riddley Walker (1980) by Russell Hoban, 2000 years after the apocalypse in England. A strange anarchical society that lives in the ruins. The whole book is written in a dialect out of which the reader can pick the twisted remnants of concepts from our own time.
Dark Universe (1961) by Daniel F Galouye, post-apocalypse, people live underground in a medieval society. The most striking thing is that there is no light, people use their enhanced sense of hearing to echo-locate and the very concept of vision has been forgotten. But then outsiders break into the underground world...
Across Realtime (1991) by Vernor Vinge, a story that goes from the near future when the world-changing discovery of how to create stasis-fields is made, through apocalypse and on into the far future where a few survivors use their stasis-fields to skip through millions of years while they try to recreate humanity.