Hi,
Did the issue occur before? Have you made any changes before the issue occurred?
First we can try audio troubleshooter and check if it helps.
No sound or Sound is missing on Windows 10/8/7 computer
http://www.thewindowsclub.com/no-sound-on-windows-8-7
In addition, more often than not when a device isn't working it is because the driver has become corrupted, please update the driver to the latest version or try compatibility mode and check the result.
You can also download the latest drivers depending on your PC model from DELL official website.
Support for Inspiron 1420
http://www.dell.com/support/home/us/en/04/product-support/product/inspiron-1420/drivers
Please Note: Since the websites are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.
Best Regards,
Tao
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