Werlis Sumer said:
I have checked but the Realtek sound drivers for the mentioned model is not listed or is unavailable.
You installed an operating system on the laptop that does not have driver support for that OS. If the Vista drivers don't work, you will have to live with the system as it is or go back to XP. You may be able to find some drivers by doing a web search for the devices using their HardwareID from device manager. Most often the video card and sound card are the ones with the most issues.