Microsoft Outlook stores local copies of all email messages, calendar events, etc. To enforce privacy and data protection, these files can be protected by passwords. You will be asked to enter a password to access the contents of the personal folder, each time you set a password for the .pst file and try to open the file. Therefore, if you lose or forget the password, it will no longer be accessible. You should keep trying to enter the correct password. However, if all your attempts fail, you should look for a better solution: the Account Live com password reset.