Iphone 4 mic problem

[Maxtrin]

Hey guys this is my first thread so here we go.
I have put a new lcd and touch on my iphone 4 for about 3 months ago and now my mic stopt working, any ides

I also changed a lcd touch on an iphone 4 last week and the same happend to that one.

Pls help me

 

[Herbert]

I've called my mom's phone and when I call her i can't hear her and she can't hear me. I tried putting the phone on speaker and it is still mute. Also, the phone is not in mute. I went to the voice memos app and I recorded myself. The mic indeed works and I played it back and I heard myself. I've played music on it and it works just fine.