Help Cant hear during calls on my s4, not sure if due to whatsapp?




I have a samsung s4. Whenever I make a call the person on the other line cant hear me nor can I hear them. My mic and speaker work fine, I know this because I can still record videos and hear them. Recently I downloaded whats app and have been making calls through there as well, my calls on there work perfectly fine. Today, I did a factory reset on my phone. Then my calls worked perfectly fine. However all of a sudden I cant hear again during calls. I'm not sure if this due to that fact that I received a call from whats app and it may have messed up something with my phone? I literally have no idea. Please help! Much appreciated