First, search for and find the operating system file you want to install.
Do a backup of your device first, using Desktop Manager > Backup. Close Desktop Manager upon completion.
1. Download the OS file to the PC then install it to the PC by running (double clicking) the file you downloaded. 2. Go to c:\program files\common files\research in motion\apploader and delete the file named "vendor.xml." 3. Plug in BB and double click on "Loader.exe." It's located in the same place as the above vendor.xml file.
Your OS install will commence. Be patient, this process can take 45 minutes to an hour.