For example, if spell check is not working, Word could be set to the wrong editing language. A simple setting might have been changed, or the language settings may be off. Exceptions may have been placed on the document or the spell-check tool, or the Word template may have an issue. Then, in the left menu, click on Language.
However, you can easily change the spell check language in Word. I want to change the spell-check language in Word 2011 for Mac.