Outllook 2002

I have a machine running Microsoft Outlook 2002 that does not have a battery backup. When the power flashed the other day, the user lost his complete email box. His personal folder file (PST) is now a 0Kb file and was over a gig. Does anyone know where his data may be. I am assuming that it is cached somewhere on the drive and could be sitting there. If so where and how do I recover it?

Thanks