asking to enter password for apple ID "(null)"

so my iphone is asking to enter password for a null apple id, it is not letting me use a different apple id. No apple id is showing under my name in settings and also i cant access sign in & security when ever i tried to open it enter password for apple ID "(null)" is popping up it only allows me to type password for "(null)" which DO NOT KNOW and i cannot use a different apple id and it seems like i cloud is also not responding i even tried to reset the iphone it asked to enter apple id for null but this time it gave me an option to use a different apple id so used mine this time it send me an verification code after i entered it says icloud not responding.