A number of my clients have brought this problem to my attention – in their Genesis-based site, suddenly their right sidebars had moved to the left of the content, and they had a new ‘Secondary Sidebar’ pop up at the bottom of the old sidebar.
If you go look at Genesis > Theme Settings, you’ll see it’s missing the Layout information completely. Below is what it should look like:
This is easy to fix. You’ll need to download a fresh copy of Genesis from StudioPress (even if your version of Genesis is completely up to date).
Make a backup of your site so you can roll back if needed. Then switch from your active child theme to a different theme (any theme like Twenty Sixteen will do).
Then, delete the Genesis theme (don’t worry, your settings will be saved!). After that you’ll want to upload the zipped Genesis file.
Once it’s uploaded, reactivate the child theme, and go check Genesis > Theme Settings. Your layout options should be back and the sidebar issue fixed.