Thanks Cas
But replacing the faulty drive with a new one is simple enough. But it doesn't solve the problem.
The issue is the lost photos and, No, they are not in the cloud and most of them are not in friends' collections. And, Yes, he should have had a backup but, like so many PC users, he was unaware of the need for it until this appalling situation faced him.
As others have said, Windows 10 updates should not cause disasters like this.
In my opinion, his only chance is to send the drive to a dedicated file recovery company. Even there, given what I was seeing, I think his chances are slim.