Unplug and reinsert the headphones
Restart the phone
Clean the headphone jack or charging port
Check for moisture and let the device dry completely
Try another pair of headphones
Blow out dust gently with compressed air
Toggle Bluetooth off and on
Turn off headphone mode in sound settings if available
Update the phone software
Clear the cache for the sound or system app if supported
Boot into safe mode and check if a third-party app is causing it
Reset network or sound settings
Perform a factory reset after backing up data
Visit a service center if the symbol stays on