Change the template that is used to display the content of the page. If the templates contain the same content elements then the content will be visible. Any content that doesn't have elements will not display that content but the content is not deleted. If the template is changed back to the previous version the the content will become visible again.
A template is a page design containing layout, editable and non editable content, and special features and functionality.
Every page uses a template. Some templates are used by many pages, some are only used by one page (ie: the Home page).