Stella's ost-to pst converter software converts all of your ost files to a pst format. Stella ost to pst converter software converts all of your ost mailbox items into an Office 365 account. Stella ost to pst converter software converts any unmounted or corrupted files into a pst. This software can convert any version 32-bit and 64-bit of an ost file.

You can find more information at this link.

 https://www.stelladatarecovery.com/ost-to-pst-converter.html