I had this coming up once... I had to do the procedure to "reset" my save. Basically:
- Quit 7 days to die
- go to %appdata%\7daystodie\saves\<Region that your save is in>
- Copy your save folder and rename it as "<game> backup"
- make a note of the save game name (<game>), and delete your original game folder
- Go into 7 days to die, create a NEW game with the SAME "<game>" name, in the SAME region (mine was in North Xamopa County)
- Quit the game
- go into your "<game> backup" folder
- Copy all the files (not the folders) into the "<game>" folder
- go into the "<game> backup\Player" folder, copy contents to your "<game>" folder
Now here's where it's going to get hairy. You'll want to copy the contents of the "<game> backup\region" folder into the "<game>\region" folder... but one of the regions is probably causing the issue. If you're lucky, you can copy all of them with no problems. If there is a problem, copy the .rg files until you find the problem one and leave it out. Pray it isn't the one with your base in it because these files save all the changes to the tiles you've made. If you can copy all the regions, the game should load without issues.