You can find the product key in one of the following locations:

• Sticker on the CD case or other packaging.

• Certificate of Authenticity.

• Confirmation email message received from an online purchase.

If it's hard to read the product key on your packaging, use this guide to help you tell the numbers and letters apart:

If your Office product key doesn't work, or has stopped working, you should contact the seller and request a refund. If you bought a product key separate from the software, it's very possible the product key was stolen or otherwise fraudulently obtained, and subsequently blocked for use. Unfortunately, there are many dishonest sellers who offer stolen, abused, or otherwise unauthorized Microsoft product keys for sale. Sometimes these product keys are printed on counterfeit labels or cards with a download link to Microsoft software, and sometimes they're distributed with software media that is unauthorized for resale, such as promotional media, original equipment manufacturer reinstallation media, or other Microsoft program-specific media.