Rpbert Miller, here is what apple says :"
You may be able to reset the passcode by restoring the device.
Connect the device to the computer with which you normally sync and open iTunes.
Note: If iTunes prompts you to enter the passcode, try another computer that you have synced with. Otherwise, go to "If you have never synced your device with iTunes", below.
Right-click the device in the left column and select Back up.
When the backup is complete, select Restore.
When finished, restore from your most recent backup.
You may be able to reset the passcode by restoring the device.
Connect the device to the computer with which you normally sync and open iTunes.
Note: If iTunes prompts you to enter the passcode, try another computer that you have synced with. Otherwise, go to "If you have never synced your device with iTunes", below.
Right-click the device in the left column and select Back up.
When the backup is complete, select Restore.
When finished, restore from your most recent backup."
If you do not have access to the computer you normally use to sync, follow these instructions.