how To update/ReInstall BlackBerry Operating System

Here is a giude how To update/Reinstall BlackBerry Operating System.

1. Connect your device to your computer.
2. Open the BlackBerry® Desktop Manager.
3. Click Application Loader.
4. Click Start in Add/Remove Applications or Update Applications.
5. If necessary, perform the following actions:
6. If the Device Security Password dialog box appears, type your device password. 
7. If the Communication Port Selection dialog box appears, specify a communications port. 
8. Perform any of the following actions:
9. To add an application that appears in the list, select the check box beside the application.
10. To add an application that does not appear in the list, click Browse. Double-click an application loader (.alx or .ali) file.
11. Click Finish.

Without desktop manager read this

• Download & install the blackberry flashfile (no need install blackberry desktop manager)
• Delete the vendor.xml file located in c:\program files\common files\research in motion\apploader
• With battery Connect your BlackBerry device to your computer
• Run Loader from c:\program files\common files\research in motion\apploader & click Next
• Select all software you want installed.
• Proceed to the end portion untill you see the "Finish" button
• Very IMPORTANT. do not hit the finish button, instead select the ADVANCED button.
• Make sure both boxes are checked.
• Proceed until it ask you if you want to automatically back up and restore, Select DO NOT AUTOMATICALLY BACK UP MY HANDHELD then next.
• Wait for Your device's software has been updated successfully