I have been using my Office 2010 for years but just over a month ago I started getting warning messages that I needed to provide a product key for this application. This has been counting down for 30 days and has now said that product activation has failed. It is maybe a co-incidence but about this time I got a file sent which had  an enhanced/later version of excel and after opening it I think this problem started. How do I get rid of the red banner saying activation failed please?

Hi,

This issue may be due to some factors. Please try the following methods and check they are helpful:

Method One:

Please see the KB, and run the Online Solution Wizard  for a step-by-step solution is available to resolve this problem.

Method Two:

• Open Programs and Features under Control Panel
• Right-click on Microsoft Office 2010 > select Change
• Select the option to Enter a product key > Continue
• Enter the Product key to update and close the wizard once the configuration complete
• Restart any Office 2010 application to activate

Method Three:

Connect Microsoft Customer Service Center(http://support.microsoft.com/gp/customer-service-phone-numbers/en-us) to get more detailed help.

Similar issue:

http://answers.microsoft.com/en-us/office/forum/office_2010-office_install/my-product-key-for-microsoft-office-suddenly-not/f96e7e3d-b2a3-4d35-bc80-0544e735a4a9

Regards,

George Zhao
TechNet Community Support