The vibrate setting has stopped working. Vibrate doesn't work at all. Is there a way I can fix it?

Please try resetting the phone but this will reset all the settings to factory default.

Steps to Reset Settings

This resets the phone to factory default settings.

1. Unlock the screen by touching Lock or pressing the Unlock Key on the left side of phone, then touch Menu to access the menu .
2. Touch the Settings & Tools icon.
3. Touch Phone Settings.
4. Touch Security.
5. Enter lock code. The default lock code is the last 4 digits of your phone number.
6. Touch Reset Default.
7. Touch OK after reading the warning message.
8. Touch Revert. A confirmation message is displayed briefly before the phone resets itself.