If you want to import your OST file into PST? then I would recommend you to use SysInspire OST to PST Converter tool. By using this tool you can convert OST files into PST and also 15 additional formats like PST, Office 365, EML, EMLX, HTML, MSG, CSV, VCF, Yahoo Mail, IMAP Account, Gmail, Zimbra Desktop, and many more. The software is the simplest interface due to this anyone can use it if he belongs to a non-technical background. It can also give you the free version.