Fix a Corrupt Outlook Data File

If you get an error message when starting Outlook that suggests that the data file is corrupted or can't be opened then generally the best thing to do is to allow Outlook to automatically re-create the file. Obviously, this is something that should be done when the machine is attached to the network.

If an error message appears, it will very often reference the data file. If not, the normal location for Outlook data files is:
c:\Users\[Username]\AppData\Local\Microsoft\Outlook

The data file will be a .ost file and is generally named as:
[email address] - [username].ost

To replace a corrupt data file:

1. Exit Outlook, Lync and anything else that accesses the file
2. Navigate to the data file location and rename the file - for example, prefixing the name with OLD_
3. Restart Outlook - this will automatically re-create the data file and synchronise it against Exchange

Note that rebuilding the data file can take some time, depending on the size of the mailbox and network conditions. During this time, normal email traffic to/from the account could be delayed so it may be worthwhile using OWA instead.