Hi shuvobd7, 

Dell has not tested Vostro 1400 with Windows 8. For more information on this, you may refer to link: http://dell.to/W0DnZT 

You can try installing the audio driver for your computer in compatibility mode for Windows XP that might work. For more information on compatibility mode, you can refer to link: http://bit.ly/WcIF2t 

You may also try installing Windows update and see if it makes any difference.

Please reply for further clarifications. 

The Vostro has the Sigmatel 92XX integrated audio. This works with Windows 8 without an additional driver on all the systems I've tested.

First run the Intel Update Utility: http://www.intel.com/p/en_US/support/detect/ 

This will see if there are any updates for the Chipset (which should be installed before the rest of the drivers) and some of the other drivers.

If you have the nVidea video card get the driver from nVidea: http://www.nvidia.com/object/notebook-win8-win7-winvista-64bit-310.90-whql-driver.html

Next check the device manager for any errors, see instructions here: http://en.community.dell.com/support-forums/laptop/f/3518/p/19473458/20278980.aspx#20278980

What is listed under Sound, Video and Game Controllers?