This usually happens when you were using a theme before that had a page template that no longer exists.
To see if this is the issue, try the following:
1. Go to the “Pages” area of your Dashboard, and find the page you’re trying to change the layout of.
2. Click “Quick Edit”, and then under “Template”, choose “Default Template”.
3. Now save, and access the page. You should now be able to use the layout options with no issues.
Let me know 🙂