Are there people who can’t talk?

Answer

Not being able to talk is also called aphasia and is often the result of a stroke (cerebral infarction or haemorrhage). Simplified proposed:

The so-called sensory aphasia: the word formation (in thoughts) is affected. One can still speak but rattles off.

The so-called motor aphasia: people still come up with the word make the speech apparatus is paralyzed. So one can (almost) say no more.

In both cases, the hearing is intact, because it is located in a different brain region.

There are other cases of speech disorder in which the vocal cords are affected (trauma, cancer, …).