Can't hear sound on internet video

[slafa23]

I cannot hear any sound on video on the internet. For example, I can see a Youtube video but I can't hear the sounds. This happens on all websites. I can however hear sound on non-internet programs, liek iTunes.
Any suggestions?

 

[Tmagic650]

Run a program like CCleaner and get rid of all the cookies and temp files on your system

 

[Po`Girl]

There`s the registry solution HERE and the Codec pack solution HERE