Category not Displaying

I have ONE category which is not showing up in the category list, so the only way for a reader to view those posts is to click back through ALL of the past posts. (Yes, there are posts in said category!) Any ideas? I’m thinking perhaps there is a setting someplace which I inadvertently messed up but, if so, I don’t know what/where it is. Or perhaps there’s a glitch in a php file someplace that I could easily alter?