First of all, thank you
"recuperation" for addressing my problem.
I apologize for my "computer ignorance" in not properly understanding your instructions. I realize how basic my training is, and I asked for help without analyzing all the aspects of my problem. I've never been in a situation like this: thinking in a language, translating it without knowing the real meaning (what the reader understands) of the words used, receiving a reply, translating it into my language, and understanding it (matching the meaning of the person answering me). I think you should accept that translation and understanding are sometimes not the same thing.
I managed to recover the files using the Lazesoft Windows Data Recovery Free program from
https://www.lazesoft.com/lazesoft-windo ... -free.html. This program offers to detect files and copy them to another disk. And without touching the contents of the corrupted HDD, it was able to back up all the files (there were 30,123 of them). After running CheckDisk and Defraggler, and analyzing the disk as I learned in this forum with HDD Guardian Toolbox and CrystalDiskInfo, I decided to give it a second chance.
Thank you for your time and interest in my problem. I will continue to work on this forum because I recognize that what is received with altruism should be made available to those in need.
Antonio (from Spain)