Go with eSoftTools OST to PST Converter Tool for solving your problem, it smoothly fixes the error Outlook OST file in use and cannot get accessed. It easily converts damaged OST files into PST, HTML, EML, EMLX, Yahoo Mail, Gmail, MBOX, Zimbra, Office 365, etc. After the conversion, you get an option to split the large-size of PST files into small-size of PST files. If you want to know more about the software then try the free demo version of this tool, it helps to give some information on how it works.