If you have a mold or mildew problem in your home you will want to use the best chemicals to get rid of it. Mold can destroy the structure of your home and affect your family's health adversely. There are different chemicals you can use depending on where the mold is growing.
Normally the transition from a spoken to an extinct language occurs when a language undergoes language death while being directly replaced by a different one. For example, some Native American languages were replaced by English, French, Portuguese, Spanish, or Dutch as a result of colonization.
Old English is a dead language. No one, not even the children of the most fanatical Anglo-Saxonists (though some of us are working on it) grows up speaking Anglo-Saxon as a cradle tongue. But it is nevertheless worth learning to pronounce the language, and not only so you can impress people at cocktail parties.