Exchange OST (Offline Storage Table) files can sometimes become inaccessible or corrupted due to various reasons. To recover data from an Exchange OST file, you can follow these steps:

Use the Inbox Repair Tool (ScanOST.exe or ScanPST.exe):

a. Locate the Inbox Repair Tool (ScanOST.exe for Outlook 2007 and earlier versions or ScanPST.exe for Outlook 2010 and later versions) on your computer. The tool is typically found in the installation directory of Microsoft Office.

b. Close Outlook if it's open.

c. Run the Inbox Repair Tool by double-clicking on the executable file.

d. Click the "Browse" button and select the OST file you want to repair.

e. Click "Start" to initiate the scanning and repair process.

f. The tool will attempt to repair any issues found in the OST file. If successful, it will create a new usable OST file.

Use a Third-Party OST Recovery Tool:

a. If the Inbox Repair Tool doesn't resolve the issue or if it fails to recover the data, you can consider using third-party OST recovery software.

b. Research and choose a reputable OST recovery tool from a trusted vendor.

c. Install and launch the OST recovery software on your computer.

d. Follow the software instructions to select the corrupted OST file for recovery.

e. Start the recovery process and wait for it to complete.

f. The software should attempt to recover and extract the data from the OST file, allowing you to save it in a usable format, such as PST.

Convert OST to PST:

a. If you're unable to repair the OST file directly, you can convert it to a PST (Personal Storage Table) file format, which can be opened in Outlook.

b. Use a reliable OST to PST conversion tool. Several options are available online, both free and paid.

c. Install and launch the OST to PST conversion software on your computer.

d. Follow the software instructions to select the OST file you want to convert.

e. Specify the destination folder and file format (PST) for the converted file.

f. Start the conversion process and wait for it to complete.

g. Once the OST file is converted to PST, you can import it into Outlook to access the recovered data.

Hope This Helps,
Peter