Edit: There's an even easier way to install PhotoRec now, assuming you have installed Homebrew, and you're comfortable in the command line:
brew install testdisk sudo photorec
Then follow the prompts to start recovering files.
As a photographer who's taken and processed at least 200,000 photos in the past couple decades, you'd think I have a solid workflow that results in zero lost files... but you'd be wrong. 99% of the time, I follow the workflow:
- Import photos from memory card.
- Make sure backup of imported photos completes (so I have two local copies—I also have one copy back up to a cloud storage provider, so two local and one cloud backup).
- Format the memory card.
A lot of photographers shoot with two memory cards, and have photos written to both—that way the 2nd card would be a double-failsafe. But for most jobs, I don't do that. And one of my digital cameras doesn't even have two memory card slots, so this isn't an option!
Anyways, more often than I'd like to admit, I do something dumb, like: