The Inbox Repair tool called scanpst can be located in different places depending on your version of Office

If you search the Microsoft Support website it seems to be closely guarded secret.

Try looking in the following locations..... ( I'm sure you will find it )

Outlook 2007
32-bit Windows; C:\Program Files\Microsoft Office\Office12
64-bit Windows; C:\Program Files (x86)\Microsoft Office\Office12

Outlook 2003
32-bit Windows; C:\Program Files\Common Files\System\MSMAPI\<locale ID>\scanpst.exe
64-bit Windows; C:\Program Files (x86)\Common Files\System\MSMAPI\<locale ID>\scanpst.exe

Outlook 2002/XP
C:\Program Files\Common Files\System\MAPI\<locale ID>\scanpst.exe

Outlook 2000
C:\Program Files\Common Files\System\MAPI\<locale ID>\NT\scanpst.exe

Outlook 97 / Outlook 98
C:\Program Files\Common Files\Windows Messaging\scanpst.exe