How does the moon turn into a new moon?

Answer 1

The moon doesn't 'turn into' a new moon, or anything else. The term 'new moon' is used when the moon is on the same side of the Earth as the sun. When that happens, the lit side of the moon is completely facing away from the earth, and the bright blue daylight sky prevents us from seeing any part of its dark face.

Because the ancients thought that the moon had disappeared completely, they often used the term 'new moon' (or something similar) to describe the first thin crescent that would appear the following day.

Answer 2

A new moon occurs when the moon is positioned between Earth and the sun, so the sun's light is not reflected by the side of the moon facing Earth. This alignment causes the moon to appear invisible or as a thin crescent in the sky.