There are lots of professional software present online that can help you to convert OST files into PST Format? Then I would like to share here such an effective tool named as
ZOOK for OST to PST Converter. It can easily convert OST files into PST format. The software also supports to repair damaged OST files and recover the data.
It is a multi-supported email application which can easily support all the version of MS Outlook’s OST file and directly import the resultant PST file. It is a windows supportable utility which can easily installed on any version of Windows operating system i.e. Windows 10, 8.1, 8, 7, and all below versions.
Check for more details at:
Easily Convert OST files into PST format 
