First of all, the audio used to play from the speaker but whenever I connected a headphone or speaker in the I, the sound didn't came. So I installed a realtek sound driver to fix this (actually I didn't find any relevant driver for my sound card so I installed it hoping it would show some light)

When I rebooted the system, my sound is completely gone and now ubuntu does not detect any sound devices in my system. I clearly installed wrong driver, now I need to remove and go to previous stage and find a correct driver.

My laptop is: Dell Studio 1747, uses a speaker Creative Labs Sound X-Fi MB Sound Blaster and the chipset is INTEL PM55.

How can I fix this?