|Hi, you can check the following information.|
For PC users:
1. Click "Start".
2. Select "Run".
3. Type: sndvol32
4. Click "OK".
5. Make sure the following are not muted and the volume is up
for "Volume Control" and "Wave".
If you're still having trouble, check to see if your system
meets these requirements for running the video player:
1. Macromedia Flash Player 7.0+ plug-in
2. Windows 2000 or higher with latest updates installed
3. Mac OS X 10.3 or higher
4. Firefox 1.1+, Internet Explorer 5.0+, or Safari 1.0+
5. Broadband connection with 500+ Kbps
Videos on YouTube are streamed through an Adobe Flash
player. For the best viewing experience, we suggest you
install the latest version of Adobe Flash after removing any old
versions you've installed.
Hope it helps.