how to unlok an ipod

If you mean that you've forgotten the passcode lock to unlock the iPod then you will need to connect it to the computer that you normally sync to and you should then be able to reset the iPod and restore/re-sync your content to it (http://support.apple.com/kb/HT1212) - you may need to put the iPod into recovery mode in order to be able to reset it : http://support.apple.com/kb/ht1808

If you do it via a computer that it's not synced to , and which therefore doesn't have a backup on it, then :

If you restore on a different computer that was never synced with the device, you will be able to unlock the device for use and remove the passcode, but your data will not be present.