Q: My iPad doesn't have "lock-unlock" icon on general setting . Why?

If you have the original iPad, that feature was not available, but you are showing iOS 7.0.4 in your tag line profile. If you have any iPad newer than the original iPad and you don't see that in the settings, you can make it appear when you put a Smart Cover or any cover with magnets on it. You can also run refrigerator or other small magnets along the side of the iPad and the setting should appear.