Have an LG E980; receive text messages, show notifications is on but don't receive a sound or sign that I have a text message. How to fix???
Welcome to the forums!
Open the messaging app > settings > notifications > sounds. Check to see that you have a notification tone set. If still not sounds then go into the device settings > sounds > volumes. Make sure the volumes for notifications is set all the way up.
One of those two settings should fix it for you - let us know if you have further questions.