How To Restore Active Directory Using Backup Exec

Hi Guys,

 i having a problem, i Have a Windows 2003 Server and a Backup Exec 2010 R2

i am in a company that every week is made a backup of System State on a external Tape (SCSI) with Backup Exec.

I had a problem in my Active Directory and i want to restore using backup exec, but in a security mode the services don't work.

The Windows Backup Software can't detect my external tape. and i don't know what to do more.

Can i use in any mode Backup Exec to Restore my System State?? or it's impossible???