As someone pointed out earlier in the post, around the 12th century translaters substituted a J for the Y as in latin, and a v for a w, and came up with Jehovah.
Where did you hear that?
Note that Jehovah started with an ' i ' in Latin and the ' i ' in Latin had a ' j ' sound. Ever watch "Indiana Jones and the Last Crusade" where Indiana steps on a ' j ' instead of an ' i ' in an effort to "walk with God."
In time, God's name came back into use. In 1278 it appeared in Latin in the work Pugio fidei (Dagger of Faith), by Raymundus Martini, a Spanish monk. Raymundus Martini used the spelling Yohoua.* Soon after, in 1303, Porchetus de Salvaticis completed a work entitled Victoria Porcheti adversus impios Hebraeos (Porchetus' Victory Against the Ungodly Hebrews). In this he, too, mentioned God's name, spelling it variously Iohouah, Iohoua and Ihouah. Then, in 1518, Petrus Galatinus published a work entitled De arcanis catholicae veritatis (Concerning Secrets of the Universal Truth) in which he spells God's name Iehoua.
The name first appeared in an English Bible in 1530, when William Tyndale published a translation of the first five books of the Bible. In this he included the name of God, usually spelled Iehouah, in several verses,# and in a note in this edition he wrote: "Iehovah is God's name . . . Moreover as oft as thou seist LORD in great letters (except there be any error in the printing) it is in Hebrew Iehovah." From this the practice arose of using Jehovah's name in just a few verses and writing "LORD" or "GOD" in most other places where the Tetragrammaton occurs in the Hebrew text.
In 1611 what became the most widely used English translation, the Authorized Version, was published. In this, the name appeared four times in the main text. (Exodus 6:3; Psalm 83:18; Isaiah 12:2; 26:4) "Jah," a poetic abbreviation of the name, appeared in Psalm 68:4. And the name appeared in full in place-names such as "Jehovah-jireh." (Genesis 22:14; Exodus 17:15; Judges 6:24) However, following the example of Tyndale, the translators in most instances substituted "LORD" or "GOD" for God's name. But if God's name could appear in four verses, why could it not appear in all the other thousands of verses that contain it in the original Hebrew?