If you have accidentally deleted an episode of podcast show and want to download it again,
you can tell iTunes to update the podcast and get the lost episodes back.
You still have to re-download the lost episodes, but at least you didn’t have to re-subscribe to the whole podcast.
First, make sure that the podcast is collapsed (the small grey triangle next to the name of the podcast
is pointing to the right). If it is pointing down, click it to collapse the podcast.
Now, hold the Option key (the Shift key on Windows) and click the triangle again to expand the podcast and tell iTunes to get a list of all the episodes. You should now see the familiar orange circle with white arrows next to the name of the podcast, and iTunes will tell you it is updating this podcast in the message area at the top.