Unfortunately, ebay removed this feature a couple of years ago or more. It was very useful for those mistaken deletion moments and was one part of the site that actually worked. You could go to your Unsold Deleted page and just tick the ones you wanted to restore and they'd come back to your Unsold page. But, as usual, ebay decided they knew best so they just removed it one day with no forewarning and not even an announcement. It has been requested multiple times that they reinstate it but they take no notice.
