Does The iPhone 7 Plus LCD control the sound?

Does the screen work at all? And the screen doesn't have anything to do with sounds. It sounds like the audio ic solder contacts have come loose. This is a common problem with the iPhone 7/7 plus. You will need to have replace the audio ic and most likely run a jumper wire because it has a history of pulling the contacts off of the motherboard on 1 or 2 spots. If you get the screen replaced and your earpiece speaker, speaker and even your microphone don't work and the speaker symbol is greyed out. And siri doesn't work. That's what is wrong with it. I would recommend a couple of places to get it repaired. Jessa at iPad rehab ipadrehab.com or Jason at sts telecom ststelecom.com they are the top in the field and most people don't have the experience to do this type of work. It takes micrsoldering skills and expertise to do it correctly.