Read the full details at KB17542 - How to reload missing BlackBerry smartphone data into the BlackBerry Manager ... however here's an example of how to actually use it.

Download the BRK Tool SyncRequest.exe and run the command: SyncRequest -n SQLServer -db BESMgmt -sync "Handheld Agent" -value_type emailaddress hdawg@port3101.org

Where:

-n = hostname of SQL server hosting your BlackBerry Configuration Database
-db = name of your BlackBerry...

Ok, this is blatant thievery from KB15871, but I've seen this a few times recently and figured it was worth noting.

Unfortunately, there isn't an automated way to do this from the BES ... The posted resolution is:

<content> To resolve this issue, delete and undelete the Desktop [SYNC] service book on the BlackBerry smartphone. Have each BlackBerry smartphone user complete the following steps:

1. Go to Options> Advanced Options> Service Book and highlight

...