Ubuntu 10.04 sound us not working?

I had installed ubuntu 10.04 but unfortunately found no sound .. but when I put my earphones I can hear something but still it is not normal .. I can hardly hear something . anyway when i download python and change vref from 80 to hiz in node 19 .. the sound is working correctly .. but when i reboot ubuntu .. I found no sound again and i have to download python again every and each time .. can any body help ??