If you've lost or deleted songs or other media in your collection, you might be able to get them back.
To restore music you acquired from Zune Marketplace
To restore podcasts from Zune Marketplace
If you have an active subscription to a podcast series, the most recent podcasts from that series may be re-downloaded automatically. However, if you kept any past episodes, you will need to manually re-download those lost episodes to restore them to your collection. For more on podcast subscriptions and downloads, see Subscribing to Podcasts.
To restore items from your computer
If you accidentally deleted music or video files from your collection but did not delete them from your computer, you can restore them to your collection with just a few clicks.