Corrupted INDD and IMDL File

Hello everyone,

Here is the problem: I can open my InDesign file, but the file shows scrambled letters, stretched letters, a lot of white space, etc.  I can't select most of the text, if I can select a word or so, text shows black, so it isn't a matter of text being white...

BUT... The Story Editor (Cmd+Y on a Mac) shows the text. So everything is there, but the display in InDesign seems to be corrupted.

What I have done already to troubleshoot: I have saved my INDD file into an IMDL file, opened it, renamed it, saved it, reopened it, but it is still corrupt. I have a backup file of the INDD file in question in the form of an IMDL file, but this file is also corrupt. I have saved this IMDL file as an INDD file and done the same as above, but also the backup IMDL file remains broken. 
Since the Story Editor shows the text, I got the idea to open it up in another program named Affinity (I know that this is an Adobe forum, but I think this information is important because), the program opened up the IMDL file, and everything displays and works. However, I'd like to continue working in InDesign, but I don't know how to go about this problem. I have reinstalled InDesign, updated it as well. I have also reinstalled older versions to see whether this does the trick. It didn't. I am out of options.

Attached are three screenshots showing how it looks like. One screenshot shows also the Story Editor.

Has anyone another trick up their sleeve? 

Thank you!