One of the ways i have found to try and fix this, is open your 7 days to die save folder find that save game that is bugged cut it from your save folder and paste it somewhere else usually the desktop then run 7 days and click new game with the same name as the one that bugged enter the game then exit 7 days open up your save folder again open up the save file you just created then delete all the files in that folder.
open up wherever you put the original save folder and open that folder cut all the files from in that folder and paste them into the new save game you had just created.
then run 7 days and see if you have your original save game back.
I'm not sure if this will help you but you have nothing to lose.