Check steps below for OS upgrade Blackberry

Step #1

Before starting make sure that BlackBerry Desktop Software is installed on the computer.

Step#2

Make sure that you have installed updated device software installed in your PC. Check this link to get update device software from carrier OS download site.

Step#3

Users can perform a full or selective backup of the data using the Backup and Restore tool in BlackBerry Desktop Manager by completing the following steps:

1. Connect the BlackBerry device to the computer running BlackBerry Desktop Manager.
2. Open BlackBerry Desktop Manager.
3. Double-click Backup and Restore.
4. Select Backup to perform a full backup or select Advanced to perform a backup of specific databases.
5. Choose a location to save the backup file, then click Save.

Step#4

To perform a clean install of the BlackBerry Device Software, perform the following steps:

1. Connect the BlackBerry smartphone to the computer and open BlackBerry Desktop Manager.
2. Double-click the Application Loader icon.
3. Click Next to start the installation process.
4. Type your BlackBerry smartphone password, if prompted, and click OK.
5. Click the check boxes next to the names of the applications you want to load, and then click Next.
6. Click Advanced, and then click the check box beside Erase all currently installed applications.
7. Click Next.
8. Click the check box next to Do not automatically backup the application data during the loading process.
9. Clear the box next to Backup and restore applications installed wirelessly.
10. Click Next > Finish.
11. When the process has completed, the message The loading operation was successful will appear. Click Close to return to BlackBerry Desktop Manager.