Missing grammar file in Word 2004?

[dramaqueen]

I'm an editor and heavily depend on spelling and grammar check. I'm currently editing a manuscript broken into 15 small word docs of about 8 pages each. Although the "check spelling and grammar as I type" option is checked, it has stopped checking either. Even when I run a manual spell check, it does not point to clearly incorrectly spelled words. And just a little while ago, when I tried to run the spell check again, it said "Word cannot find grammar file for English (US)"! What's going on?!