The fact is the very exact, original pronunciation or vocalization of God's name is lost. But the original name is not.
You see, each language have have their own translation of the name 'Jesus' but 'Jesus' is neither the original vocalization of Jesus' name, its not the way they described it in Hebrew or in Greek way back then, yet we "accept" the name 'Jesus' to pertain to Jesus. This is also true with the other characters in the Bible like 'Moises', 'Jeremiah' and 'Peter', these are 'translation' of their names in English, and this is also true with God's name.
Taken from the Tetragrammaton, 'YHWH' which has also equivalent with 'JHVH', some early language scholars choose 'Jehovah' as the translation of God's name. They use 'Jehovah' to represent God's name in translating the Bible in other languages and this translation has been accepted and used for many centuries. Centuries after 'Jehovah' became the popular translation some Hebrew scholars then recommended that the name of God be translated to Hebrew as 'Yahweh'.
If the name 'Jesus' is 'accepted' to be the name of Jesus in English, why not use 'Jehovah', which has been 'accepted' and used for centuries to represent the God's name in English and other languages and Yahweh to represent God's name in Hebrew.
This brings to the conclusion that although 'Jehovah' might be not the exact pronunciation of the name of God but it is the exact name of God.
Now, why others are not used to the name 'Jehovah' or even admit that God's name is Jehovah the fact that they know that it is really the name of God. Because it is already widely used by Jehovah's Witnesses around the world. That if they used it, this might prove that the Jehovah's Witnesses are right.