The back button and toolbar are not displayed on the new activity, how to solve this problem?

Question

Java

I took this menu https://github.com/tral/MaterialDrawerFragmentSample as the basis for the project,
but when I open a new activity but there is no top bar and back button, I read and tried different methods, but it doesn’t appear, tell me what’s the matter, otherwise it’s already night it killed (if you need the codes of my project, I can provide what would become clearer