URGENT....URGENT......URGENT

I have ASDM server on VM system ( release .9/1.9 ). A root user in Aix who had
ability to destroy archive and backup filespace, This user had destroyed
a filespace . But this filespace was use by users to archive many big
files. The root user didn't know that archives files destroyed too.
Is there a recipe to repair this CATASTROPHIC ERROR.

I do DUMP DB my server Tuesday morning,and the destroy occured this morning
( friday ). There's no activity on Archive tape since Dump db. When this event
occured the server do Space Reclamation on archive tape...

                   Thank for your answer quickly ....... Yves