this is the point of a
backup drive... it's a
backup of files you have on your mac (or another drive). it's essential, always, to have your data in (at least) 2 places, so if one of them fails... you have it elsewhere.
but that doesn't help in this moment. try this:
https://www.alsoft.com/DiskWarrior/
it's saved me on 2 occasions, when i had a drive failing.
THEN get two drives: 1 for photos, and 1 to BACK THE FIRST DRIVE UP.