This happens sometimes, I do not know why. Suddenly I miss some of the theme resources without that they have been deleted.

This time I miss them in all styles on one project. Can I just copy them over from the resources of fresh install? 

Today I created the theme ID 39! Happens always after disable IN_DEV mode when working with plugins. It doesn’t happen with apps. 

The quick “fix” Is to create a new Default theme in Manual mode and change the default_theme ID in init.php with the new theme ID.

@Adriano Faria, I have the issue on the live server that had never IN_DEV. I better open a ticket as I would not like to mess with live project.