look in the following location:
C:/Program Files/Autodesk/Maya8.5/docs/Maya8.5/en_US/wwhelp/wwhinpl/js/html
There should be a file called "wwhelp". If so, open it and see if it takes you to your help files. If not do a file search for "wwhelp".

If you still can't find the file, insert your Maya CD and see if you can reload the help files.

hope this helps.

I'll try to dig up a little more info for you in the meanwhile.