Why can't we use "doesn't talk" instead of "don't talk"? when referring to he/she why is "doesn't talk" wrong?

Why can't we use "doesn't talk" instead of "don't talk"? when referring to he/she why is "doesn't talk" wrong?

e.g. When you are talking in class and your teacher said: "don't talk please." Why didn't she use "doesn't talk" in that case?

Why we can't use "doesn't talk" instead of "don't talk"?

When refer to she or he why "doesn't talk" is wrong?

Why can't we use "doesn't talk" instead of "don't talk"? when referring to he/she why is "doesn't talk" wrong?