This two-part blog series will outline some of the recovery options available to administrators in the event that one or more public folders are accidentally deleted from the environment. The first part will explain the options, while the second part will outline the architectural aspects of public folders that drive the options.
Read more at source: http://blogs.technet.com/b/exchange/archive/2012/02/06/recovering-public-folders-after-accidental-deletion-part-1-recovery-process.aspx