Nahhh, just a hardware failure on an old drive. I knew it was coming, bought a 1TB USB back-up drive and backed everything up on 7/10, then didn’t have the wit to do daily backups afterwards...
If it’s an iMac, and hence the backup disk can be left plugged in and turned on full-time, shouldn’t the automatic “no action required” system of Mac OS’s “Time Machine” suffice?
Ah the old oopsie..... has happened to all of us at least once ;)