Your iPod lock how can you unlock it?

If it's under warranty, contact Apple or schedule an appointment to take it to your local Apple retail store to have a Mac Genius (technician) look at it. If it's not under warranty, and it's the center scrollwheel button that's giving you a problem, you may want to try to take something thin and plastic, like the corner of a laminated card, and gently work it between the edges around the button to see if you can coax it out. Good luck!