Why is it in a call or skype call no sound is recieved except in speaker mode

[AC Question]

so basically when i call someone or someone calls me either via phone number or skype number i can't hear the other person no matter what, not unless I'm in speaker mode. it worked before and i know it's supposed to be on the top speaker and kinda silent thought it only plays when it's in speaker mode. the phone mode thing doesn't work any more. Help"?