Sound not working

I have an ASUS laptop that has Windows 10 installed on it. It just recently updated. I was having issues with the sound the day it updated. It would say that my sound was working, but neither my laptop speakers or my headphones had sound. After the update the icon for volume had a little red "X" next to it. I have tried restarting my computer, using the troubleshooting software on my computer, and going into the sound settings. Nothing has helped. When I go to Manage audio devices it says, "No audio devices are installed". I have also tried using the RealTek HD audio manger app, but it doesn't open. Please help.