Ci-dessous, solution donnée par le lien en question
Something to try...
Create a new folder MS Help OLD.
Copy/paste all the files from...
C:\Users\All Users\Microsoft Help
...to the newly created one and delete all the ones from...
C:\Users\All Users\Microsoft Help
Open one of the Office programs and click on the help function.
(Make sure you are connected to the Internet.)
The program will then downloaded a new set of help files and after rebooting the PC go back and see if the Help files are still there. If that works then delete the folder you created to store the OLD ones