Why can I see screen but no sound

LEGOtrains123xl we need to know if your TV is truly a LG 60LM6450 60inch LED since that is the device you picked. Make sure that you check your settings menu to ensure that your speakers /audio is even turned on. If all of your settings are good. Try an external sound bard or some headphone and see if you get audio with that. If all of it still does not work, you may have issues with the main board since that is where the audio is located. Of course you want to make sure that your cable top box ( if you are using one or similar cable company box) has been reset. Isolated audio issues like this one are not very common.