Undo the most recent content change you've made on your site. Once you have made a change, a notification will appear which will offer an undo option (see below).
Not every action can be undone
The undo option won't appear if the action can't be undone
Image content: the "title" and "description" fields are shared by every occurrence of that image so changes to these fields can't be undone. For example, if you add the same image twice, it will share the same name.
Changes to other image fields, including changing the image itself, can be undone.
PayPal Buy Now: the "account email" and "currency" fields are shared by every occurrence of that button so changes to these fields can't be undone.
Changes to other fields available can be undone.
Deleting pages and making changes to page settings e.g. page names.
Deleting content widgets
Disqus: the only setting within Disqus is the "shortname" for the chosen Disqus account.
Blog search: this content has no settings.