What Happened to the Word WHO?

The word WHO was originally pronounced HO, H-W-O. But remember the spelling convention reversed those first two letters, giving us the modern spelling WHO. And that caused the W sound in the middle to disappear. That's what happened to the word WHO spelled WHO. The same process also explains the pronunciation of the related words WHOOM and WHO's,. as well as the word WHOLE, WHO whole. They have also lost their W sound.