What I would do is as follows:

If this happened recently, I would go back to the restore point previous to my problem

If I am not mistaken, I think the Office install disk has a Repair available, so I would try this

Failing this, I would reinstall Office by uninstalling with Revo and select total, because if you do a normal unstall/reinstall Windows remembers previous settings (in its registry) so I would accomplish nothing with the generic unstall/reinstall