Unlocking an outlok.pst file

I experienced a hard drive crash and replaced the drive. I can access the old drive as asecondary device and recovered most of my files. However I must have set some of my files as private and I cannot recover my e-mail history as the folder “Application Files” denies me access to the Outlook.PST file. Is there any way to unlock this folder and its files so I can recover my e-mail history? I have tied setting up the same logon account as before but still cannot unlock these files!