Assuming you are talking about Microsoft "Word" have you tried locating it in
Control Panel -> Programs and Feature
Most MS Office products come with a "Repair" function, whether individual or the whole productivity suite.
IF you select it in Programs and Features you should be able to use the "Change" button to evoke the "Repair" option.
You might give that a go.
Failing that you might want to perform an uninstall, reboot and reinstall.
Not particularly elegant but it generally works, most of the time.