12-28-2012 10:17 AM
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Go to Options > Applications > See if BlackBerry Messenger is listed there , if it is then delete it from there.
KB10040 : How to view or remove installed application on a blackberry smartphone
Then Reboot your Device by removing the Battery while your device is POWERED ON ,After reboot from your BlackBerry Browser browse to www.blackberry.com/bbm and download BlackBerry Messenger again.