The contents of a folder disappeared
Do you remember some of the filenames?

Try to enable Spotlight to search documents, and use it to find the file you misplaced. You should be able to find it if it’s still inside your Documents folder.

Using Terminal

My last attempt would be using Terminal to list all the files containing your files content keywords. Run Terminal and enter command below (replace your file content with some of the unique keywords in your lost documents:

grep -R 'your file content' *

It should display all the file it can find on your User folder. If it still can’t find the files, they’re most likely gone forever.