According to me, you can search a unique third-party tool of OST to PST Converter tool which migrates data from offline OST files into PST, EMLX, EML, MBOX, MSG, HTML, HTML, and etc. formats. The software has the latest features as specified below.
• repair & fix each type of Outlook error and converts corrupted items, and etc.
• conversion of mailbox items such as Emails, folders, contacts, properties, attachments and etc. of .ost files into Outlook PST files.
• again show deleted items of .ost file into outlook.
• export database from offline ost to pst outlook and 15 plus file format.
• unique option to split large Outlook PST files into small Parts.
• No requirement of MS Outlook.
The PDS OST to PST Converter provides a more safe way to restore and replace faulty OST files without losing or altering data. Data from OST files, such as mail Inbox, Outbox, Deleted Items, Sent Items, Journals, Tasks entries, Notes, It effectively works with all the versions This product permits you to work in disconnected mode when your Outlook isn't associated with the web association.
Know more info- http://www.perfectdatasolutions.com/convert-ost-to-pst.html