LG E400 User Manual page 124

Troubleshooting
Message Possible causes
The screen
does not turn
Proximity sensor problem
on when I
receive a call.
No sound Vibration mode
Hang up or Intermittent software
freeze problem
122
Possible corrective measures
If you use any protection tape or case, check to see if it has
covered the area around the proximity sensor. Make sure
that the area around the proximity sensor is clean.
Check the settings status of the sound menu to make sure
you are not in vibrate or silent mode.
Remove the battery, insert it again and switch on the phone.
Try to perform a software update via the website.