Sound suddenly stopped working on computer

Thanks for responding to me... so I tried going into the device manager but I really wasn't sure what I was suppose to do when I got there. The instructions said to check for conflicts and when I opened the device manager it did not tell me there were any conflicts at all. I did see Sound, video and game controllers but it didn't say anything about a conflict or anything like that. It then asked me to ensure that my drivers are properly installed and that the programs that I have recently installed are not conflicting with the drivers configurations. I have know idea how to check these things, sorry. Also the last things said to check my sound card which I also do not know how to do. The only thing I can give you for more information of what was going on when it happened is that it was working and then I left the computer for a while and no one used it or touched it and when I came back to it the sound had stopped working. I do have anti-virus on my computer Avast! and it says I do not have any viruses. I did have a bad virus fairly recently where they had to wipe out the entire computer, but the anti-virus has said I have not had any viruses since then. Do you think these things could be related? Thank you again so much for your help!

You go into control panel, find the sound settings & open. When you see the speaker input option or options....meaning to say it says like computer speaker or realtek speaker etc. You can right click on them & click test to see which one makes sounds. Ive had this happen 10 times in my life on different computers this fixes it every time. The computer somehow changes the speaker setting to be to a speaker that doesnt work or isnt connected. So once you see which speaker makes noise when you test right click & choose to make it the default speaker