1. Install your carriers hand held software on your PC
2. Install the Desktop Manager on your PC.
3. Launch your Desktop Manager
4. Connect your BB to your PC directly, no hub.
5. Do a ctrl+alt+del on your BB
6. When the hour glass appears on your BB double click the App Loader icon within the Desktop Manager.
Should ask you to confirm your PIN do so and follow the process through to reload the OS.