My Ssiri does not detect my voice on my iPhone 6 plus

Hello!

My phone is iPhone 6 Plus A1524 iOS 11.1.1 NGAJ2LL/A 64GB

My specific problem is that Siri does not detect my voice / voice commands and

the other person can not sometimes hear my voice on whatsapp video call.....but

This is not the same with FaceTime which has no problems

And if I use earphones I don't have that problem no matter what app I use

btw...my Touch ID does not work...says "Failed"

Is it a software or hardware problem? And what can I do?

I don't have a guarantee/ warranty or any protection plan...thank you