Lots of tool available in online market who claims to Fix OST errors and Convert into PST file format without any data loss risk. But I want to suggest you this Regaintechnologies OST to PST Converter software easily Convert your OST file into PST and many other file formats like: PST, EML, MSG, HTML, MBOX, EMLX, vCal, vCard and PDF formats. This software has simple and easy GUI Interface where user can easily Operate it without any technical skills. You can easily run this Application all the versions of Windows OS.
Try this software free demo version from here: https://www.regaintechnologies.com/ost-to-pst-converter.html