I opened a Word file using the TextEdit app, highlighted what I needed from the article, pressed "Save" and moved it to the desktop before I closed the file itself. And then I tried to reopen it but there was nothing highlighted and all of my work has been deleted!
TextEdit makes versions of files, so you should try that first using the File menu in the app.
- File -> Revert To ->
If that fails, then go to your TimeMachine backup or other backup of that file.
Worst case, use spotlight to search for other copies of that file if you don't use either of the native backup options for reverting file changes on macOS.