If you're looking for the best way to convert or recover OST data to PST or other formats, you've come to the right place. I recommend using the
SysInspire OST to PST converter app, which is a third-party tool. It provides the best error-free conversion and translates a large number of OST data products to Outlook PST, Office 365, Live Exchange Server, and EML, MSG, and HTML formats without interruption. It recovers previously deleted OST objects and restores data from a distance. It is the foundation for all versions of Outlook and the Windows operating system. It provides a free preliminary rendition that allows you to convert the first 50 items in each folder.
Here is the solution to OST is in use and cannot be accessed