missing ipad

You will only be able to located the iPad using Find My iPhone if the device had Find My iPhone activated before the loss, is powered on, and is connected to the Internet. If any of those things are missing, then you will not be able to locate it. If the device is a Wi-Fi only device, then it would have to connect to a known Wi-Fi network to locate.

If the service had been deactivated, you would not be able to see the device in FMiP in the first place to even try to locate it. More than likely it's turned off or just not connected to the Internet.

If your FMiP was activated before the loss, then to de-activate FMiP, it will need your Apple ID & password.

There is no way around that.