Kerry you can try to Extract Emails From OST File using the inbuilt repair tool i.e Scanpst.exe. Might be it will help you out. you can also check the steps if you like by the following link.
https://support.office.com/en-us/article/Repair-Outlook-Data-Files-pst-and-ost-25663bc3-11ec-4412-86c4-60458afc5253