If you have turned Off V/O and are having issues with entering the Passcode...
Try a Reset... Try again...
Reset ( No Data will be Lost )
Press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears. Release the Buttons.
http://support.apple.com/kb/ht1430
If no joy...
Connect to iTunes on the computer you usually Sync with and “ Restore “...
http://support.apple.com/kb/HT1414
If necessary Place the Device into Recovery mode...
http://support.apple.com/kb/ht4097
Note on Recovery Mode.
You may need to try this More than Once...
Be sure to Follow ALL the Steps...
Once you have Recovered your Device...
Re-Sync your Content or Restore from the most recent Backup...
Restore from Backup
http://support.apple.com/kb/ht1766