If Word files are the issue, do they work in File Explorer's viewer pane? If they don't, it's a Word problem and can usually be fixed by repairing/reinstalling Word.
I rebooted explorer cos that started showing similar issues and it seems to have been fixed now;
strange that only some files were affected
thanks anyway
Different file types are displayed via different software. Word docs are displayed via a component of Word, in this case. Others may be built-in, or via plugins, or via other software, depending on the file types involved.