Deleted a podcast's show in iTunes and now want it back? You can resubscribe, of course, and download everything again — or hold down the Alt (Mac) or Shift (Windows) key while clicking the black triangle in front of the podcast to collapse and expand its episode list.
Did not even delete mail in Yahoo! Mail and now have to get it back?
›› Messages have inexplicably disappeared from your Yahoo! Mail account? You emptied the "Trash" folder with an important message inside? Here's how to undelete mail and recover lost messages by restoring Yahoo! Mail to a previous state.