Menu options not clickable on Microsoft Office

Hi All,

I have been facing trouble with the Microsoft office product, I have purchased the product key and it is a genuine product. I am unable to click on any of the menus (eg. Format/Delete menu options in excel).

These options are all visible to me, however, when I click on them they do not work. Some items on the ribbon work (like some formatting options, etc) But I cannot use conditional formatting, and other menus.