Maybe there will be some kind of meteor strikes.....
There were some kind of major catastrophe which eventually turning upside down almost everything. Buildings destroyed. Earth blasted upwards. Debris flying everywhere. People tried as hard as they can to save themselves. But many perished and the outcome is devastating. The great buildings of humanity were turned into rubbles. Things that once were 100 ft high above the ground might ended up 100 ft below. Perhaps a large area of valley might be became several hills. Imagine this as a world catastrophe which only a few of 6 billions of people survived. Technologies were lost although few might be still available. So people ‘restarted’ again. Cities were rebuilt albeit this might take decades or even centuries. Rather than pursuing technologies, people will ended up with survivability first. No big deal. That’s what people required. It’s essential. Tho, survivors are getting older and older until they’re dead. Less and less people remember what was the world like before the disaster. Things going on until people able to live rather peaceful and adequate provisions along with the growing population and the advancement of technologies. Professions became broaden like what we have currently. There might the reemergence of archeology which people start digging up the earth to find the past after 2000 years. There might be findings that these archeologists feel amazed. Imagine if they found a buried room where some bones were found which presumed to be a male and along side with him are a bunch of miniature idols or figurines made of plastics that representing female while there might be also some humanoid form of robots of unknown history…