I've installed Backtrack but I can't figure out how to play mp3files. I've installed ubuntu-restricted-extras,lame, libmp3lame but still won't work(I have Rhythmbox player, I've also tried Amarok). Any ideas?
You need to install gstreamer libraries, take a look at this link
apt-cache search gstreamer-0.10 to find related libs, and install them with
apt-get install XX