I was really amused reading the question (If God doesn’t exist, what will happen after you die?) because I was thinking, “How would God’s existence or absence influence what happens after you die?”
Anyway, the first thing that would happen after my death is my consciousness would come to an end forever.
Another thing that would happen is that my name, my personality would all die with me. As soon as I die, I would become a “body” or a “corpse” (laas, shav in Nepali).
Then I would be cremated. My body would turn to ashes in hours. People would think I have rested in the sky. If I had decided to donate my organs after my death, my organs would be saving someone. If my body goes for donation to a medical institute, my “body” (body is what they would call) would be studied.
If I met death horribly, for example, sunk down into a lake or swamp, my body parts will decay therein or become fossilized. If I drown into a river, my body might be swept downstream, discovered horribly swollen, or may never be found, dismembered and fed off by fishes and even water itself. Still some of my body parts would be fossilized.
If my death occurs by being crushed over by a building or a rock or a mountain of a vehicle, my body parts might scattered here and there. It would never be donated but could be cremated, if lucky or would be fossilized.
It got too gory even for my own taste. Maybe you believe that God will take you or your soul will get to heaven (or may go to hell or remain in purgatory.) I can’t be as sure about that. I have never seen God do that yet except in some movies.
Originally posted as an answer on Quora.