recovering deleted files external HD

Can you open the trash, then "sort" the files in there in any way that makes them identifiable -- as to "where they came from"?

I'd try that, then select the files I wanted to save, then use the "Put Back" command.
It's in the file menu of the finder, or you can right-click on the file(s) and select Put Back from the contextual menu.

If it's necessary to do this "one file at a time", then that's what I'd do.
The idea is to save them in whatever way works for you.

 

This might work:

· Open the trash

· Go to File<< Find and the Finder window for Trash will change. Choose "Trash"

· Click the search criteria box and choose "Other" from the drop down. Select Date Added from the list. Pick a date and click OK

That will list everything moved to Trash on that date