Audio problem

I purchased a logitech Z-640 a while ago and I used it with my motherboard's audio since my motherboard could do 6 channel 5.1 speaker sound. Now, a couple of days ago I notice that no sound is coming out of my rear speakers...I individually check all the connections and the rear speakers work but when I put it in the proper connection hole it does nothing.

So yesterday I decided to get a soundcard. A creative soundblaster 24 bit live. The good thing about this sound card is that the same colors that are on my speaker connections are on the card so I don't have to guess anything, just plug and that's it. Now when I installed all the drivers, etc. and I individually test each speaker they work...but when I put a song or something only the center, and the 2 front speakers work...this is really pissing me off....any ideas as to what it may be? Should i disconnect and reconnect the speakers? Because it cannot be the soundcard it's brand freaking new.

your songs are in stereo and don't use the rears. those are mainly for movies or games. try putting your speakers in 4.1 mode or eqivalent if you really want to listen to music out the rears. usually this is not done though. the rears are pretty much just for movies and games man. It's working right though.