The easiest and safest way to change OST files into PST is to use the dedicated SysInfo OST to PST Converter. Manual solutions can be tricky, especially with large or multiple files, and may put your data at risk. It allows you to transfer emails, contacts, calendars, tasks, and notes into PST with no data loss. It also gives options to convert into other formats such as MBOX, EML, PDF, and CSV, or move your data straight into platforms like Office 365, Gmail, or Yahoo.
Read more: https://www.sysinfotools.com/ost-to-pst-converter.php