When you find that the phone speaker is not working anymore, firstly, make sure that you have checked the most obvious options such as volume, Bluetooth, and silent mode. Temporary glitches can also be solved by restarting the device. When those measures are not effective, there is a possibility of dirt or debris hindering the sound in the speaker grill. In more serious cases, you may need professional help to fix phone speaker (https://devicefixes.com/blog/speaker-repair/) problems caused by hardware damage or internal connection issues. The device can also be opened by a repair tech, and the speaker component examined and replaced in case the device is not functioning properly.