Lost MS Office Product Number

[Still Learning]

I have my Office disk but not in its case. The case, apparently, has the
product code. My computer was recently reformatted so Office needs to be
reinstalled. How can I install without the product number or how can I
retrieve it?

 

[David Webb]

You cannot retrieve it once the HDD has been reformatted.

See the section titled, "Replacement product key", in this article:
http://support.microsoft.com/default.aspx?kbid=326246