Please note Microsoft Office (Word) is individual product which is separate from Microsoft Windows.
From your description, it seems that you have bought a computer which has the trial version of Office preinstalled. And now the trial has expired (usually will be expired in 60 days).
To continue use Office product, either input a valid product key to activate/convert the Office to a full product.
Convert a trial version of an Office 2010 suite or program to a full retail version
Or try Office Professional Plus 2013
Download Microsoft Office Professional Plus 2013
TechNet Community Support
A new Office has arrived, try it now.
A beautiful Start. It begins here. Windows 8 and Windows RT.
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