My spell check suddenly quit working, and I followed all the advice in this
thread to no avail.
Someone mentioned (possibly in this thread or perhaps another as I've been
looking all over) that there might be a bad add-in. I was going to disable
add-ins one by one and see if spell check started working again.
I clicked on the Office button, went to Word Options, then Add-ins. In the
drop-down menu at the bottom of the screen for Manage ___ Add-ins, I noticed
a choice for Disabled Items. I clicked that ... and there was the solution to
my problem. enUS was listed as a disabled item because it caused a problem
the last time it was used. I enabled it, and spell check is back.
I have no idea how or when Word disabled the add-in and haven't had any
problems that I'm aware of before it was disabled.
Perhaps this will help someone else ...