The Trash bin is located above the left-hand folder tree when you're in the Site Content area.
To restore one or more items from the Trash, select the checkbox next to the items and click the Restore button at the top of the list.
Note for users - If you don't see the the Trash bin, please contact your CMS administrator for assistance.
Note for administrators - Users require at least one of the following Site Role abilities to access the Trash bin:
View and Restore only assets the current user deleted
View and Restore all assets in the Trash