If you have done a backup with activesync you should be able to restore it. First off, make a copy of your AS backup file on your desktop to a separate folder. Next, delete your partnership in AS if you have one out there. Then put your PPC back in the cradle. When AS tries to create a new Partnership select connect as Guest. Your PPC should now connect to your computer as guest. Now go and try to restore your AS backup by going to Tools -> Backup/Restore. Goto the Restore tab and use the browse feature to find the backup that you want and then restore.
See if that works for you.