Panic! File gone missing

He can probably unerase the memory card using Data Rescue: https://www.prosofteng.com/downloads/ provided he hasn't added any new date to the memory card. There is a free demo of Data Rescue that will allow you to recover one file without payment.

 

Good call by JohnDS above.

Wherever he "sent" the memory card to, he'd better call quickly and get it back!

 

It is simply deleted. There is no clipboard or space where these would be kept. Your colleague probably copied the file, not moved. That makes the deletion logical from Finder’s standpoint. I cannot reproduce this with a file move, as Finder complains with an error message (presumably because it attempts to move the file back to an unavailable location).

 

If that's your colleague's Standard Operating Procedure, then it needs to change.

Files aren't safe until there's at least one duplicate somewhere else. Preferably two copies in two separate places. This is especially true for external media, such as SD cards, USB drives, etc.


If the hasty deletion and reformat was for security reasons, as in the data needed to be kept from access by others, then learn to make and use encrypted disk images. These are made using Disk Utility, using instructions described here:
https://support.apple.com/en-us/HT201599

You can also google search terms:
macos encrypted disk image