Passcode Locked or Disabled
If nothing else will let you unlock the device - after so many unsuccessful attempts will be locked out - You have to restore the device within iTunes. You want to use the same computer that you always sync with so that you can restore your app data and settings. You can restore with any other computer, but you will lose everything on the Device.
Instructions can be found here.
http://support.apple.com/kb/ht1808