No internet sounds and system sounds

Hi,
i have this problem for a week now, but now its getting really annoying. My problem is that any sound played via internet browser doesnt play, for example i open some video on youtube, video plays but sound doesnt. Ive tried it in several browsers, but still the same problem. Other sounds in programs like winamp or pidgin do play normally. But i found out that windows system sounds dont play, too.
I checked every sound setting in control panel, and everything seems OK. Ive also searched on internet, and ive seen that some people had this problem, too, but i couldnt find any solution.
Im using Win XP.
Anybody can help? Thank you in advance

 

Maybe do a system restore to a date over a week ago would be the first\simplest thing to try.

 

thanks for reply, ive tried it twice.
but ive already solved the problem - i reconnected some of reproductor cables and now it works but thx anyways