I have a Microsoft Lumia 640 XL and I can not hear sound in the earpiece. How can I fix this?

[Windows Central Question]

i am having microsoft lumia 640 xl . i am not able to hear sound in the earpice. why is it so?

There is no sound in the earpiece when I call but there is sound in the speaker and there is sound when I plug the headset. this happened after when my phone fell down slightly. what could be the problem