Can you open the file? Export as IDML, open that and save as new INDD.
If not, go back to your last backup as no other possiblity is available, except to use a blind-open-script.
But you should always inform us:
- OS and Version
- InDesign Version
Unfortunately there's little that we can do about a corrupt document. If you can share the file, we can take a look and see if the file can be repaired. Please email your InDesign file to email@example.com and we will take a look at the document.
If the file is larger than 10 Mb, you can zip (and password protect) the file and upload to Creative Cloud account (or Dropbox) and send us the document link.