Why I can't hear people talking I have to put speakers on

Ear piece speaker is most likely clogged or damaged. If you test the audio recorder you can see if you can hear yourself or not . Another test you can do is to run the device in Safe Mode (I believe you hold the power key down and you can activate safe mode). Test from there and see if results are different.

If muffled, try to clean out the earpiece using a soft brush, try not pushing into the ear piece.

If it’s still not functioning, it’s most likely damaged.