As the earpiece speaker assembly is mounted and connected on a flex cable ribbon, so in this kind of design, the audio signal may loss if the flex cable is being damaged or cut and this will result to no audio sound can be heard over the earpiece speaker. On the picture repair guide below you can trace the earpiece speaker line paths across the flex cable before trying to replace it with a new one; but make sure to test and check the earpiece speaker first before doing anything further.
Now, if the speaker and the flex cable seems both working fine, you may then proceed to check the line filter coils as indicated on the picture guide.
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Replace it with similar value, you may find it on other non working PCB board of other Nokia mobile phone old model. Check the line paths across the pin connector to the filter coil, apply a a tiniest magnetic wire jumper if found open or cut.
If all of the above does not fix the problem, the last part will need extra precaution and expertise or you may end up killing the phone.
But this will only happen occasionally and so rarely and may occurs if the phone's history is damaged by a liquid (water damaged) or being accidentally heavily dropped.
You may proceed to rework, re-ball, clean the PMIC (Power IC), the earpiece audio signal is connected to the terminal (C2- positive and D3- negative) of the PMIC. While the PMIC is being remove make sure to trace this lines through to the filter coils from those earpiece audio ball bumps from the PMIC before mounting it back to the main PCB board.