some waffle first
bios onboard sound can interfere with sound
wrong kernel modules can interfere
wrong settings and configs ditto
In particular...mixer settings.
I suggest you look at http://sidux.com/index.php?module=Wi...=MixerSettings
and there is a link to multiple pages at the botton called sound master.
yours is a rpm system but I am suggesting alsa-utils and its associated mixer....alsamixer ....and other apps are the best to trouble shoot.
There are many pages there...so feel free to peruse to get the gist of what to test.
2) gstreamer...namely the libgstreamer acts as a backend to software that needs the gstreamer plugins.
Its possible you have accidently un-installed some plugins.
try downloading independent software that can play multimedia
I suggest vlc