Congratulations, you have become another victim. PST file corruption is irreversible, at least not all free software found on the Internet. Some network mailboxes will automatically save copies of emails sent by computer terminals through SMTP. You can log in and have a look. If there are, move them to your inbox and download them to your computer. PST (or OST) files can be reduced by compression, automatic archiving and new folders, but each file is at risk of being damaged. After the disaster, I not only left one copy on the server, but also made three copies locally. I hope you can learn from it.