1. My Outlook 2010 Pro Plus Address Book vanished giving a totally blank list of all my previous contacts.

2.  All my Personal Folders vanished with only the default folders listed.

3.  Suddenly, Outlook began listing many old emails ... more than 500 emails.

4.  Kaspersky active and did not report any malware or virus to cause this major upset to my Outlook.

It sounds like you somehow deleted or reset your current account configuration. It's impossible to tell from the information provided.

At this point, restoring your data from a backup might be the quickest solution.
See: http://www.howto-outlook.com/howto/backupandrestore.htm

Hi,

1. What type of account are you using in Outlook? Exchange, POP or IMAP?

If you are using an Exchange account, switch to Online Mode to check if the Address Book is visible.

2. Check the folders on your Webmail/OWA, do they still exist?

3. Do the old emails exist on Webmail/OWA?

4. The anti-virus program may not be related to this issue.

Kindly answer the questions above to help me have a better understanding about the scenario, thus I can provide my suggestion.

Regards,

Melon Chen
TechNet Community Support