I had to remember an old Outlook error when closing the data file incorrectly .ost either .pst . Now this problem is not very common to me, but before when the systems were still 32-bit (x86) and antivirus programs were not so good and mail files often exceeded all possible limits. We often had to "save" mail because the archive of emails was only in the data file. Data files of 2 types:

1. The PST data file is a local archive of the mail database. it is permanent and emails stored in this file are not required to be saved on the mail server.
2. The OST data file is nothing more than the server's mail database cache. In other words, this file contains a cache of emails located on the mail server.(you can safely delete it if an error occurs)

And so basically you need to restore the PST file, for example, and let's look at what we should do in case of an error "the data file does not open".

And so to restore the file, we need to find a special utility that is part of Office. In my case Office 2010 is installed the utility is located on the path:

C:\Program Files (x86)\Microsoft Office\Office14\SCANPST.EXE

After starting, we need to specify the corrupted file, it is located by default on the path:

C:\Users\user_name\appdata\local\microsoft\outlook\***@****.ru.ost

After clicking the start button , the analysis process will start:

When completed, the scan statistics will be displayed with the result. In my case, there are errors , we specify whether we need a backup and start the recovery process:

When the recovery is complete a dialog will appear closing which we can safely launch Outlook,