There are some emergency rescue tools available, but so far only for Windows damage.
Found it.
https://forum.audacityteam.org/t/corrupt-or-otherwise-broken-audacity-project-recovery/64162/1
Depending on how desperate the situation is, you can transfer the show to a Windows machine and then run the Windows repair tools. Once the show comes back (if it does) you can transfer it to your working machine’s internal drive and continue to edit.
Being obsessive, I would leave the show on the Windows machine as an “Air Gap Firewall” backup.
Make sure all your raw, pre-edit recordings are available on WAV files so if some serious damage happens to your edit, you could create the show again. For example, I can announce a chapter of my book, Stop, File > Export it as a perfect quality WAV (Microsoft) 16-bit file and save it somewhere safe. Edit a COPY of that file and clear up the mouth noises, fluffs, cursing, air conditioning buzzing, and other word mistakes. The Edit Master should also be a perfect quality WAV file. If the client wants MP3 (ACX-AudioBook), only then do you create a lesser quality MP3 file according to their 192 quality requirements. We should remember you can’t edit an MP3 file without the quality suffering.
Koz