The onboard soundcard "got lost", because the video driver for your gtx 650 switched the standard playback device to it's hdmi output (control panel / sound). Start with what mihir94 said, cause you probably messed up the realtek driver.
As Mihir94 wrote, I removed with drivesweep the Realtec drivers and removed in hardware the soundcard. Problem remains: Detect the hardware but after install the driver it still doesn't work. Any ideas?