Unlock a Disabled iPod
If you own an iPod Classic or iPod Nano, you can set a
four-digit security code on your device and then lock it to keep other people
from accessing it.
Disabling your iPod is a good way to protect the data on
your device, but if you lose or forget the four-digit code, you will need to
manually unlock it in order to access your music and other content.
Plug the iPod USB cable into the bottom of your iPod.
Plug the other end of the iPod USB cable into a free USB
port on your Mac or PC.
Open the iTunes application by using the dock icon
on a Mac or the start menu on a PC.
Click on the name of your iPod under the "Devices"
list in the main iTunes window.
Click on the "Sync" button to create
a connection between the computer and the iPod.
Click on the eject symbol after the syncing process is
complete, and then unplug your iPod from the computer.
The lock code has been reset; when you go to
disable the iPod again, you will be prompted to choose a new four-digit code.
Hard Reset a Disabled iPod Touch
A hard reset restores your iPod Touch to its original
This is useful when your iPod Touch is disabled and won't
turn on or off, but all your data is erased.
Luckily, you can restore your data with iTunes after you've
performed the reset.
Once you've performed the reset, your iPod is wiped clean
and iTunes prompts you to restore the settings from your last sync.
Plug the iPod into your computer and wait at least 10 minutes.
This allows the battery to recharge in case it has drained.
This could fix your disabled iPod, if the problem was caused
by a dead battery.
Click "OK" if your computer opens a "Connect to iTunes"
Depending on your version of iTunes, the message may
indicate the iPod is in "recovery mode" and you need to restore the
ITunes opens and resets your iPod for you.
Unplug the iPod from your computer if you don't see the "Connect to
iTunes" alert box.
Make sure the iPod is charged before you attempt the hard
Press and hold both the On/Off/Wake button and the Home button on your iPod.
Keep the buttons pressed.
Wait for the Apple logo to appear, it may take 10 seconds or longer.
When you see it, release the On/Off/Wake button but keep the
Home button pressed.
Release the Home button when you see a picture of a USB cable with an arrow
pointing to the iTunes logo.
Plug your iPod back into the computer.
The iTunes "recovery mode" message will appear.
Click "OK" to complete the reset.
http://support.apple.com/kb/HT1808iOS: Unable to update or restore