A few days ago, I wanted to open my old Outlook PST file, but I had forgotten the password. After a lot of attempts, I tried SameTools PST Password Recovery Tool, and honestly, it was a great experience.
User-friendly interface
No data loss
Password recovered in a few minutes
All versions supported, including Outlook 2019/2016
If you are also unable to access your password-protected PST file, then I would definitely recommend trying it once.