My iPhone 11 was stolen and the find my iphone is off on the device. Please what do I do to get this phone back?

if you report the IMEI to the police when you report it stolen in some countries they have all carriers block the phone so the thief can't use it, otherwise you should call your carrier yourself and have them block it

There is no way to track its location.

the phone cellular or landline of a friend/relative or well-wisher or maybe from a phonebooth if you live somewhere they still exist

many carriers also have physical stores