After any bad circumstances in ost file every client perfert to take right solution to repair ost file and convert ost to pst via inbuilt utilities but If they don't have adequate knowledge that they have lost their file forever. So before knowing any thing properly I must say that use third party tool. And as per recommendation , Gstech software company really a best option for repairing ost file. Company made ost to pst tool for instant recovery and conversion of ost file to pst,eml,msg and html too.
Read more- https://www.gstechsoftware.com/osttopst/
ATS OST Converter can export emails with all items from corrupt offline OST file into advanced Outlook PST file with multiple formats-" PST,EMLX, HTML, MSG, vCard/vCal( calendars/Contacts etc.) and MBOX formats. Along with it application also split large Outlook PST file into small PST file (1GB to 25GB). Download the free demo version and you will get a best chance in the trial version to convert 30 emails for free.
Read More: https://ats-ost-to-pst-converter-toolkit.en.softonic.com/
SysOZ OST to PST Converter is an incredible software that can deeply scan high-risk inaccessible OST file data and provide the outstanding process to convert/migrate any size large OST file into PST, EML, vCard, vCal, MSG, EMLX, and MBOX file formats with complete mailbox attachments.
Read More: https://sites.google.com/view/sysoz-ost-to-pst-converter