Nexus 4 - microphone don't work on calls

[AC Question]

But with other programs it works and during call enabling loud speaker call... the mic does work.
The phone had been wiped. Factory secting wipe just few days ago.
From the time it did worked till now, no additional software had been installed. And no use of headphones at all (not even for music)

Found this program on play store:
https://forums.androidcentral.com/e...droid.wiredheadphoneroutingfix&token=CHkCA0il

and tried to use it to restore audio path but doesn't seem to work.
Month ago, it happened the same and that program fixed it by resetting audio path.

Android version is 4.4.4 stock google... no modding... never done any modding on that phone

What concern me is..
1) how to fix it
2) how is possible that it happen, what trigger that problem?

thanks a lot for anyone that could give me a hint... and to anyone that just is reading

 

[B. Diddy]

What other apps seem to work with the mic? Remember that most apps that use the mic are using the secondary mic, not the phone mic. The speakerphone also uses the secondary mic. My suspicion is that your primary phone mic is faulty.