This is a known issues… it might happen to you that the iPhone stop speaking to you.
In my case in particular there was no earphone, no speaker, no sounds in the normal call… basically a completely mute phone..
i tried all the “conventional” ways of inserting multiple times the earphones, cleaning the hole with Windex etc… no luck…
So i simply tapp on:
“Settings>General>Reset>Reset All Settings”
And automagically the iPhone went back to life and start speaking to me again.. speaker, phone speaker and earphones work like a charm