How do I restore folder converted to Unix Executable on flash drive on my MacBook Pro?

in re-reading, is see your complaint is about a FOLDER that changed.

To open a folder that has been turned into an App, hold the Control key while you click on the Icon. Choose "show package contents" and what is inside the Icon (mistaken for an App) will be opened, and you can manipulate it freely.

The file itself is not likely to have been changed. Your Mac just does not know how to AUTOMATICALLY open that file type anymore.

So open it manually.