Thanks Elliot,
It turns out that I have an earlier backup of my wp-content folder.
I created a new WP install, copied the wp-content folder and inserted the backup SQL, and now I’m able run the old site and export all of my four field groups into php and use it on the live site.
However, since the problem occurred because the server could not load all four fields when I edited them, I chosed to rather recreate the flexible fields manually in new groups with the same field names.
Now my fields are automatically populated on the post edit screen, and after updating each post they are displayed just like before.
Thank you for your quick reply, and keep up the work.
