InDesign files won't open! Help!

My InDesign won't open! I tried to open them and the message says "Cannot open the file. Adobe InDesign may not support the file format, a plug-in that supports the file format may be missing, or the file may be open in another application." I am running the current version 17.0.1 but these problem files date from July 2021 and earlier. ALL of my hundreds of InDesign files prior to July 2021 are now unable to be opened! Please help if you know something that might help. My current InDesign files are working but I am afraid they, too, may soon meet the same fate. The corrupt files were only created by me and were InDesign from the beginning and not shared and stored on my iMac and my own hard disc. Even the ones on my hard disc are just as bad. Although the bad files are a few months old, I still need them critically to revise for ongoing projects. Please help shed light on this problem. Thank you.