I actually just helped someone with this on Discord.
Firstly, if you happen to be in any private maps, you'll have to re-download those to be able to see them again, try going to your character biography in game and then the home tab, hit reset home then go home. If it tells you "cannot find map file" keep reading;
If by chance you happen to still be in a black screen, lonely cave or any public maps are not showing still and you're getting the error "cannot find map file", then uninstall and re-install the game completely. Re-installing the game helped them, so I'm assuming it should help you as well if it's not a private map issue. I tried giving the map files to this person and it didn't work, re-installing fixed the issue whole, so I recommend this. (of course back up any mods and stuff you'd like to move over after installing) If you try this again, suggest making sure you've fully uninstalled the game before doing it.