3 Column Blog Became 1 Column Blog After Upgrade

I just noticed that a completely inactive blog’s format has changed from 3 columns to 1 column without any changes except for an automatic upgrade that occurred in the interim. I know that someone with more knowledge than I will see what the problem is in a few seconds. I’m guessing its something with the sidebar.php file but really have no idea. Ive completed the upgrade and upgraded all plugins. Theme is Elegant Blue

Thanks so much for your help. https://www.renodiscontent.com