In Windows Explorer, if you navigate to the following:
%LocalAppData%/StoryDev/
And tell me if,
- The directory exists, and if it does,
- The file "settings.json" exists.
The likelihood is that "settings.json" cannot be found, based on the supplied error.
If it does exist, please open the file properties and add full access permissions to the file and try re-opening Story Creator.
Let me know how you get on.