My iPhone 12 Pro earpiece has suddenly stopped working, tried all troubleshooting but still no fix

Mine too - I dropped it. Nothing to be done except an Apple repair for £469 or anout $450

Third party speaker repair may lose your front camera and sensors.

As a workaround I have set my routing to the bottom speaker for all calls as everything else works fine.

Settings, Accessibility, Touch, Call Audio Routing, Speaker