Cannot open a .OST file in Outlook 2007

35 pts.
Microsoft Outlook 2007
My hard disk had a problem and I had to back up my data in another hard disk. Once I got a replacement, I copied back my data. On opening my mails, I noted all my .PST files had changed to .OST and thus I was unable to open them. I get an error " The file you chose is not an outlook data file. You must select a new file of this type. How do i open this? Do i need to convert the .OST to .PST?

My machine is running on Windows 7 and Outlook 2007




Software/Hardware used:
Windows 7 and Outlook 2007

Answer Wiki

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If you want to backup a copy of your Outlook mailboxes. Thus, you would need to convert the Outlook OST file to a PST file. The term PST stands for Personal Storage Table’.

free convert ost to pst solution

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  • Subhendu Sen
    OST file is related to exchange server and associated with a mailbox on it. If ur profile could not redirect to that particular mailbox, u never unlock ost. There is no method to open the standalone ost file directly in OL since it is encrypted with the ES mailbox(as far as my knowledge). U need to connect the ost file to the original ES mailbox, read the content and move the information to the pst file. May be some 3rd party tools can help u. Though I am not sure whether is it helpful, but u can try MS Reference
    61,930 pointsBadges:
  • Amanda lakai
    You need to convert your OST file to PST format to access the data within it. For that you require some efficient OST to PST converter software.

    You can try out the free demo of the OST to PST converter software available at:

    You can view the preview of converted items. See whether you are able to view your mailbox items after converting the OST file to PST?
    I hope it would help you.

    2,345 pointsBadges:
  • Brijesh

    Try performing a repair on you .pst file:
    Repair Outlook Data Files (.pst and .ost) - Outlook - 
    14,435 pointsBadges:
  • Genderhayes
    Open in offline mode create a PST in Outlook 2010 open file menu click account setting tab should see Out look data files you should see  PST AND OST files
    10,050 pointsBadges:

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