Hi John,
Firstly you'd need to follow Microsoft's recovery procedures for Exchange. This assumes your entire Exchange server was never backed up up, including the System State and installation directories.
If not, read the MS guide on how to do this below:
http://technet.microsoft.com/en-us/library/bb125070(EXCHG.65).aspx
If you have all of the data backed up, you'd do the following:
1. Get the server up to OS level.
2. Restore all data (program Files etc.)
3. Restore Exchange data
4. Restore System State
5. Reboot.
If you don't have the data backed up, you'd need to get the server to the same OS level including patches, onto the domain with the same name and IP address (you might have to delete the old name out of AD first), and partition the drives as it was before. then restore the Exchange Information Store through BE. You can also look at duplicating the IS to disk which gives you the flat file. Read my article below on how to do this:
https://www-secure.symantec.com/connect/articles/restoring-exchange-or-individual-mailboxesitems-usi...
Thanks!
