Recover Emails on Exchange 2010 due to event ID FSE agent 5047

Hi,

I have received many error messages with the following event ID and Message.

Log Name : Application
Event ID : 5047
source : FSEAGENT

Transport scan engine unknown exception occurred during scan. Message will be archived to undeliverable folder and purged
 
i restarted the server and fixed the issue but i need to recover the emails .
how can i recover these purged emails.

Thanks