Okay so i have a few options you can try to fix your blackberry. If you do not have blackberry desktop manager.
Download Here: BlackBerry - Desktop Software - Canada
1. Go to "my computer" From start menu (windows XP) or Computer (Vista or Win 7)
2. Locate this folder Open up Program Files/Common Files/Research In Motion/AppLoader
3. Delete the VENDOR.XML file
4. Locate this folder Program Files/Common Files/Research In Motion/AppLoader
5. Open up AppLoader.exe
6. Plug your blackberry into the computer and open AppLoader.exe
7. Reinstall the blackberry software onto the phone.
1. Remove the battery out of your phone
2. Plug your phone into the computer with the battery out
3. Open blackberry desktop software
4. Go to options and select "Connection Options"
5. Select "USB PIN Connection" under connection type
6. Open up Application loader
7. Select the OS software you want to install
8. It will ask you if you want to automatically back up and restore-DO NOT CLICK THIS OPTION
9. During the installation process you’ll want to make sure you reinsert your battery before it is finished
I hope this help you with your problem.