If the Outlook mailbox folder get corrupted and unable to access then you will need to recover the OST files and convert into accessible PST format, you can use OST to PST Converter which is able to handle all kind of problems and export the data from OST to Outlook PST file format. It supports all the variations of Microsoft Outlook from 97, 2000, 2003, 2007, 2010, 2013, 2016 and 2019 and all Windows versions up to 10.
Visit:https://www.kdetools.com/ost-to-pst-converter.html