Reload using BlackBerry Desktop Manager or downloading the application from the BlackBerry.
Complete the following steps:
1) Download the latest BlackBerry Device Software from your wireless
service provider's web site.
2) Install the BlackBerry Device Software on a computer that has
BlackBerry Desktop Manager installed on it.
3) Connect your BlackBerry smartphone to the computer.
4) From BlackBerry Desktop Manager, double-click Application
Loader and follow the instructions in the Application Loader Wizard
to install the BlackBerry Messenger application.