To convert an OST file to PST on Windows 7, the simplest and safest option is to use an automated tool because Outlook doesn’t provide a direct export for inaccessible or orphaned OST files. You can try exporting to PST through File > Open & Export > Import/Export if the OST is still connected to your Outlook profile, but this only works when the mailbox is active. For disconnected, corrupted, or inaccessible OST files, the SysTools OST to PST Converter is the most reliable method. It extracts data directly from the OST and converts it into PST without Outlook, preserving emails, contacts, calendars, attachments, and folder structure. This ensures a smooth and error-free conversion on Windows 7.