Quick suggestions…?
Does this behave the same way on another computer?
What o/s are you using?
Has the disk been dropped? Probably not, eh?
If it helps, I don’t think these pics are lost forever. Not at all. Take this one step at a time.
And furthermore, once we’ve got the pics back, you’ll go out and buy a 2nd disk as a backup. Either seagate or wd or any other brand. Two copies on two different devices - of anything you want to keep is the order of the day!