You may use manual method but manual method is so complicated and required technical knowledge so normal person can't use this tool without any technical help. Then in this situation i recommend you to use this brilliant OLM to PST conversion software which comes with so many advanced and unique feature like- batch conversation option, save attachments, preview facility and so many. Now users can easily migrate into MS Outlook environment. This software saves the exported data efficiently from inaccessible or damaged OLM files. This can also export several OLM files to MS Outlook in a single conversion cycle. This software quickly retrieves mails, contacts, calendar items, hyperlinks, attached files and other data from OLM files.
Use this free demo version of this software which allow the user to scan and see the preview of all recoverable data. This demo version ensure the user about it function and features.