No sound on youtube

[Reece]

Hey guys, I can't able to hear any sound in all youtube videos. I'm using the Firefox. Yesterday i was getting sound properly but can't now. I haven't changed any settings and haven't installed anything new in audio device, but then why i'm getting this issue without any reason?

[Fleming]

Are sure it happening with firefox only? Have you tried youtube with IE? Does other sites having proper sound with firefox? Sometimes it happens with me also, try by right click on firefox and select Click Run As Administrator. hope it will work.

[johnson22]

It can be because of multiple reasons. In firefox some sites with multimedia content may require you to allow popup windows or cookies or that you disable ad-blocking. Try the following:

• Verify that cookies are enabled in the Privacy panel in the OptionsPreferences window. Verify that the site is not blocked in the Cookie Exceptions list.
  
• You can allow the website as an exception in the Firefox pop-up blocker. The "Block pop-up windows" option is found in the Content panel in the OptionsPreferences window.
  
• For the time being, you can disable any ad-blocking software or Firefox extensions, such as Adblock or Adblock Plus. If the site works with ad-blocking disabled, you may want to add the site to your whitelist in your adblocker filter.

[Raiz]

Refer to following similar discussion threads:

No sound when streaming with flash videos on youtube, google, metacafe
you tube no audio
no sound when surfing the internet
youtube sound problems

[deveritt]

If you are using the Windows Vista, then : Windows Vista volume mixer

1. Open Firefox and visit a site that should play sound.
2. Click the volume icon in the Windows task bar.
3. Click Mixer. The Volume Mixer window will appear.
4. Make sure the Firefox slider isn't at the bottom.

It can be a issue the Flash plugin because youtube uses Flash for video and audio. Reinstall the flash player and check whether the sound option is on or off in flash player.