One option is to reboot your phone to its factory settings. To do this, follow the instructions below:
1. Home screen-> Open the All tray-> Select settings->Security-> Security Wipe
2. The security wipe options screen will be shown. (Select all options that are available to be deleted)
3. Enter "blackberry" in the blank box
4. Select Wipe data. Then the phone will reboot when complete.
If this doesn't work you will have to replace the cursor button.