No one knows how to pronounce the personal name of God. It's called the Tetragrammaton, a $20 word made up of Greek parts that means, as you would guess, "four letters." I guess calling YHWH a four-letter word just doesn't have the same connotation as the cryptic and more snoddy "tetragrammaton."
YHWH is the transliteration in English of the Hebrew consonants. The vowels have been lost to history as the Jews did not pronounce the name for fear of taking God's name in vain. When they came to this word in the Biblical text, they would say "HaShem," ("The Name") or "Adonai," meaning "Lord."
To guard against saying The Name even more, the rabbis intentionally changed the vowel marks, replacing the original vowels of YHWH with those of the Aramaic word, sh'ma(, "the name." That is how we got the difficult pronunciation and really nonsensical word, Y'HVAH.
During the Reformation when Gentiles were rediscovering the importance of reading the Bible in the original languages, many read this word at face value, Y'HVAH, naive to the Rabbinical hedge which had been placed around God's personal name.
How did they translate it? JEHOVAH. By the time Jewish scholars explained to Gentiles their mistaken reading, the word Jehovah had gained a place in the dictionary, and it since has come down to us as meaning "God." Actually it is a non-sensical conumdrum of a word. Now don't you feel sorry for the poor Jehovah's Witnesses? They go around trying to score points with a god whose name is gibberish. Ask a JW about that next time they come by.
So if you ever meet anyone who tells you they know the secret personal name of God, you'll kind of know what's up with them. They're either ignorant, pompous, naive, or mental.
So is there any way to guess how YHWH might have been pronounced? Our best guess might be from Greek texts from the first century AD or CE, (take your pick.) Greek has vowels, and they transliterated the personal name of Israel's God as "Iave." Therefore most people guess "Yahweh." BTW, the Cherokee people have their own legends of the Creator revealing His personal name to them as "Yowah." Hmmm. Those dastardly vowels.