How can I reset the sync history for my iPhone?

On Mac:

Open Finder and run iSync from the Applications directory. Select Preferences from the iSync menu and hit the "reset sync history" button.

On Windows:

Open iTunes and choose Edit -> Preferences. Select the Sync tab and choose to reset sync history.

To reset sync history you -open itunes - devices-sync history

My Microsoft Office Outlook calendar has stopped syncing with my iphone. How can i make it sync?