I suggest you to use the eSoftTools OST to PST Converter, an amazing tool for converting OST to PST without losing any single bit of data. It is a well-known company for converting OST files to PST files format and quickly importing them into EML, vCard, Office 365, EMLX, HTML, MSG, Yahoo, Gmail, and others. It can also support all windows and Outlook version up to 10.
Read More:- convert OST to PST files
Convert OST to PST Manually
Open Outlook and go to the File menu.
Select the Import/Export option.
Choose Export to a file.
Select Outlook Data File (.pst)
Choose whether to export a specific folder or the whole account.
Check the Include subfolders box.
Next, select a destination for the Export, and then click Finish.
Regards, J Wick