Broken Widget – Article Categories

Hello,

I’ve been using the CoverWP theme for a long time. I thought I’d try changing my theme for the new year, but decided that I liked CoverWP better. When I changed it back, the widget called “Article Categories” drop down was no longer populated. You can see this on the sidebar at http://www.homeschoolingteen.com . I examined the posts while logged in as admin and they are all categorized. How can I get the categories to appear on the drop down again?

Thanks.
Happy New Year!