I'm using a Dell Vostro 1014 laptop with Ubuntu 11.10. From the time I had Ubuntu 9.04, sound comes from the laptop speakers only even when I plug in earphones or external speakers. Also, if an external microphone plugged in, it does not work. Dell even replaced my motherboard to check for hardware issues but the problem persists. So it is definitely not a hardware issue. The sound plays perfectly through the headphones in the pre-boot diagnostics. So I figure, this must be a problem with Ubuntu not recognizing my sound card.

Please try to give a solution for this problem.