You can use SysInspire OST to PST Converter Software to resolve the issue OSt file missing Outlook 2016. It is a very safe and secure software that can recover all lost OST data such as emails, journals, tasks, notes, chats, contacts, calendars, tasks, notes, attachments, appointments, and messages. You can download the free demo edition from SysInspire's official website, which converts 25 items from each folder for free.