Alt + F4 will close Word and save all open documents

without presenting you with the Save dialog.

Did you drop down the File menu to see recently saved documents at the bottom? Maybe your lost document is listed there.

Did you look up the various ways you can search in Word's File/Open dialog box in the Help file?

You can also search for documents with the Find option on the Windows Start menu. If you change your view to Details, you can sort by date.