You should be able to retrieve the most recent ones. Just go to your mailbox and click on the "my deleted posts" tab. From what I can tell there is a time limit as to how long they are kept in your deleted posts folder. I am only guessing it is on the order of 2 weeks. I could not find anything in the terms of service literature listing a duration. So if you have interest in retrieving them you will have to be fairly diligent about checking it.