you dont wrote that you have audio file in your system ,means you installed audio driver,,
answer is no so plz install audio driver ,
if answer yes just go to volume control it is stay on start bar you will see a volume symbol
double click on volume control if you see mute option bold just remove and your audio driver will be work on your system , and on your you tube will be work
if you can not listen sound , just change your spk or head phone etc.
again you can not listen sound just tell your hardware er
if you leave in Ahmadabad just talk with me on this 9824670424
i am India