A few days ago i have also suffered this issue then my friend suggested me try this OST to PST Exporter software and i tried that software and got a great result and that tool is easy to use and very secure. you can download the demo version of this software which converts few items from each folder.The application is workable with all Microsoft Outlook versions. I hope you will get the best results using this software. you can download this software from here:-https://www.betavare.com/ost/pst/
Professional OST to PST Converter from provides an easy and reliable solution to convert OST to PST. ost to pst converter free full version tool to conversion files from OST into Outlook, PST, EML, MSG, HTML, EMLX, vCal, MBOX and vCard. User can also export OST files to Office 365 that is the additional feature of this utility.