OST files are the offline replica of user mailboxes on the Exchange server. An OST file resides on the user system. So, it is vulnerable to many issues. They often show undesirable behavior such as inaccessibility, corruption, or synchronization issues due to reasons like accidental deletion of a user account on Exchange Server, virus intrusion, server slowdown or crash, power failure, etc. Under such situations, the user may have to look for options to repair or recover the inaccessible OST file.

File repair options in different versions of Outlook

The OST file repair options are different in different versions of MS Outlook. In MS Outlook 2000 and 2003, Detect and Repair tool was embedded for the recovery of data files. In MS Outlook 2007 version, the Detect and Repair tool was replaced with an Office Diagnostics tool. In MS Outlook 2010 and 2013, although the Repair option was available, it was specifically designed for repairing the Outlook installation files and registry entries. However, in the latest versions like Outlook 2016 and 2019, there are easier ways to repair and recreate OST files.

Recreate the Offline Data File (OST)

OST file is an offline version of Exchange server files. If it gets deleted somehow, the user can get its fresh copy by downloading it from the server again. The process of recreating the OST file is given below:

1. Close the Outlook application.
2. Open Mail from the Control Panel.



3. It will open a dialogue box named Mail Setup – Outlook. You need to click on Email Accounts.
4. The newly opened dialogue box Account Settings will have all the Outlook accounts. Click on Data Files, choose the OST file, and then click Open File Location (to go to the location where a particular OST file is residing).



5. Right-click on the OST file and click Delete option to delete the file.
   Note: Before deleting the file, close the Account Settings and Mail Setup windows; otherwise, the system will give an error message.
6. Start the Outlook application again. It will automatically create a new OST file for the account (downloading all the data from the Exchange server).

Repairing the OST file

The above method to recreate the OST file will work only when the Outlook account and Exchange server are in perfect sync. If the Exchange server is down or there are network issues, then the method may lead to permanent data loss. So, it is highly recommended that a competent third-party recovery tool must be used to handle the corrupt OST files. Kernel for OST to PST Converter is one of the most trusted and widely used data recovery tool that can retrieve data from any corrupted OST file and convert OST to PST file.

Below is the process of restoring an OST file and converting it to the PST file using the tool.

1. After you have installed the software, start it; the ‘Source File Selection’ window will open instantly. Here, you need to click the Browse button to add the OST file.



2. After selecting the OST file, click the Next button.



3. The Information window will tell you about the recovery process and various output formats available for saving the recovered data. Click Finish.



4. The tool scans the OST file and restores the data. Let the process finish.



5. 5. The tool has recovered all the data, and you can check all the folders in the exact hierarchy as they were in your Outlook mailbox. Check the items and see their preview also. Later, click the Save button.



6. Choose PST File (MS Outlook) as the output format.



7. Choose the various options for saving the file. Also, you can split the PST file after reaching a definite size and attach a prefix to the store name. Then click the Next button.



8. Click the Browse button to select the location for saving the PST file.



9. After saving the PST file, the tool will give you a message with the location of the PST file.