In case and if you're using stock firmware:
1. Boot into Recovery Mode
2. Perform a full factory reset by wiping /data partition.
3. Reboot and see if it fixes the problem
However, try and use a custom firmware in case your OS is causing the problem. When it comes to me, the hardware doesn't have to be necessarily damaged or affected in such a case since the phone app is on emergency calls, so it's fully accessible. I recommend checking the app settings again (maybe tapped on something accidently), but nevertheless, I prefer trying a custom Rom to verify that it's a software issue, or simply flash your stock firmware through ODIN to fix any issue if persisted.