How to unlock the code?

Ipod Password Lock
The first way is you can connect the iPod to the computer it was originally configured on, and open iTunes. When you disconnect iPod from the computer, it will no longer be locked.
You then can go into the preferences and turn off the lock. If you don’t have access to the original computer or it just does not work, you can jump to the second method.
The second way is the fix for any iPod problem, it is the classic “restore your iPod to factory settings.” That this will erase all data on your iPod and take you back to day one, but you can just add your music and data back to iPod from iTunes.
Good Luck,
I hope this helps