The mail is fine and the way back in is easier than you fear, because the PST password is one of the weakest protections Microsoft ever shipped.

Here is the technical reality: the password never encrypts your mail. It is stored inside the file as a CRC32 hash, a checksum from the 1990s. Outlook merely refuses to open the file when the prompt answer does not match. The messages sit in the file in their ordinary form the whole time.

That weakness is your recovery route. PST password tools exploit the CRC32 either by computing a working password from the hash or by blanking the stored value entirely. SysTools PST Password Remover takes the second approach, point it at the file and it clears the password so the PST opens normally, no guessing involved, seconds not hours regardless of what the forgotten password was.

After removal, attach the file via File, Open and Export, Open Outlook Data File and your 2014 self's mail is back. Since this is your own archive that is simply account recovery, the same ease is worth remembering whenever you are tempted to treat a PST password as real security for anything sensitive: for genuine protection the file needs actual encryption around it, BitLocker on the drive or an encrypted container.