4.1 working as 2.1

[bravequail]

I unplugged my 4.1 speakers(creative 4.1 4400) from my computer and then later connected them again, when i conected them only the front speakers were working. I had 4.1 working only a few days ago. I have all the cables connected yet there is no option for 4.1. Does anyone know how to fix this problem?
I have a VIA AC'97 sound card i believe.
Thank You