I am using Outlook 2007 as my mail app. In the past I have used a Microsoft exchange account from my old company. After leaving the company, I unfortunately erased the exchange account and lost all my contacts and agenda information. How I can retrieve the information from the “Microsoft Outlook offline folders” already stored on my PC.
Unfortunately, .ost files are specific to the Outlook profile and SID created for that profile/mailbox. Once the mailbox is disconnected and you try to reconnect using a non-exchange profile, or even the same removed exchange profile, you will not be able to retrieve the contents of the .ost file.
When you leave an Exchange enabled Company, the data belongs to them, not you and the SID enforces this as the case (one reason, among many, to use exchange mailboxes and not .pst files).
However, you can use an OST to PST utility from here to convert it to a .pst file, then you can import the .pst file into Outlook using File > Date File Management.