Recently I had to recover my PST file password and I did it with PstPassword utility
This utility can recover PST for all Outlook versions , from 97 up to 2007.
PST Password works as stand alone utility , no Office installation is required
Using PstPassword
In order to start using it, just run the executable file, PstPassword.exe
After you run the Password reset utility , the main window displays the list of all PST files of the current logged on user (Under Documents and Settings\User Name\Local Settings\Application Data\Microsoft\Outlook). For each password-protected PST file,
If you want to recover a password of PST file that doesn’t appear in the default list, you can press F7 and select the desired PST file, or simply drag the PST file from Explorer window into the main window of PstPassword.

To Download PST Password Recovery tool go to http://www.nirsoft.net/utils/pst_password.html