Hi. 25 character product key for microsoft office home and student edition.............I need it?

Hi,
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There is no product key on my hp pavillon dv 4000

Component ID Hardware and Software Guide 1–19 Additional Components Optical Discs Software on optical discs, such as CDs or DVDs, is included with all notebook models. n The software packaged in the “Required for Setup” bag is not preinstalled on your notebook. Depending on how you want to use your notebook, you might want to install some or all of these applications. n The software packaged in the “Save for Later” bag is preinstalled or preloaded on your notebook. The software discs are provided in case you ever need to repair or reinstall this software. Labels The labels affixed to the notebook provide information you might need when you troubleshoot system problems or travel internationally with the notebook. n Service Tag—Provides the product name, product number (P/N), and serial number (S/N) of your notebook. You might need the product number and the serial number when you contact Customer Care. The Service Tag label is affixed to the bottom of the notebook. To display the information on the Service Tag on your screen, select Start > Help and Support. n Microsoft Certificate of Authenticity—Contains the Microsoft Windows Product Key. You might need the
(Product Key to update or troubleshoot the operating system. This certificate is affixed to the bottom of the notebook. )On Regulatory label—Provides regulatory information about the notebook. The Regulatory label is affixed to the inside of the battery

The prooduct key number listed at the bottom of the notebook does not work. Any other suggestions