You can convert OST to PST format by using InQuit OST Converter you will get access.
following features: Capable to convert OST into PST, EML, MSG, PDF, MBOX, vCard, HTML.
Software Features: Support All Versions of Microsoft Outlook OST and Windows OS.
Maintains Metadata and export complete data (Emails, Contacts, Calendars, etc.). You can do the bulk conversion of the OST files and you can also recover OST files with password. Demo version is available to convert 30 emails for free.