I'm assuming the 'On My Computer' folders are those within the Outlook app, where you have your Inbox, Drafts, Sent, etc.?
On a standard build, Outlook 2011 stores it's files in the user's Documents folder, at:
Code:
~/Documents/Microsoft User Data/Office 2011 Identities
(just copy this and type SHIFT-CMD-G to open a 'go to folder' window, and paste it there)
However, the time to try the recovery option was before you reinstalled Outlook (maybe even with the simple utility provided by Microsoft called 'Microsoft Database Utility' which can be run by holding down the 'ALT/OPT key when opening Outlook)...however, the corruption might have damaged the database, and the full reinstall of Outlook might have given up and just cleared them to start afresh.
BTW, Outlook Mac stores it's data differently than it does on Windows, and there aren't the plethora of recovery tools for the Mac that there are for Windows.
Do you have any backup (Time Machine, etc.) that you can recover the database from?