Resync with outlook.
I would personally use pim backup to backup my contacts prior, just to be safe. or save the pim.vol file off the phone and put it on the card or your computer.
Here is the link to pim backup
http://www.dotfred.net/PIM/PPCPimBackupV2.8_wm2005.zip
be sure to save your backup to memory card.
Here is more info on pim backup
http://www.dotfred.net/default.htm