You should be aware that Word ignores text in all caps and certain other
options that can be selected under Tools, Options from the menu, on the
Spelling & Grammar tab. Also, system resource problems can turn off the
in-document display of spelling/grammar errors. Clicking the spell check
button on the toolbar will still find and allow you to correct mistakes if
that's the case. If that doesn't work, try going to Tools, Options from the
menu, click the Spelling & Grammar tab, and click the Recheck Document
button. This will make you recheck the entire document from scratch, but if
you accidently told it to ignore areas you now wish to correct, it will let
you bring it back.