Yes, you can do this but it depends on how you recovered your previous identity.
Caveat Emptor: always backup before trying any of this, just in case.
I'll assume that you used the Microsoft Database Utility to recover your previous identity.
- Launch Outlook and from the menu bar select Outlook, Work Offline. This will prevent email sync issues (getting new mail in the wrong identity, double items, etc.)
- Launch the Microsoft Database Utility from /Applications/Microsoft Office 2011/Office.
- You should see your current and at least one previous identity in the Utility. Select the utility that has the folder you wish to recover.
- Click the gear on the bottom left portion of the Utility window and select "Set as Default".
- Restart Outlook, go offline again and find your missing folder.
- Drag/drop the folder you want to keep to your desktop. It should create a file with a ".mbox" extension.
- Shutdown Outlook, launch the Database Utility again and reset your default identity back to the one use previously.
- Relaunch Outlook (still offline) and copy the folder back. Once you're sure it's all there, go back online and make sure new items are syncing.
Hope this helps.