Edit: Updated the link using wayback machine and copy-pasted the content in case the wayback link breaks in future.
It is actually a hardware issue. I am attaching the link that helped me to narrow down to the problem.
Copy-pasted from the link (in case the link stops working in the future):
Use this FAQ when you have no audio from both the speakers and the headphone jack. If you have no audio from the speakers but do have audio through the jack, see the Headphone Jack FAQ.
If you just re-installed your operating system and do not have audio, go directly to Section 7 of the Audio Driver FAQ.
I. General Steps
Perform these general steps in any order.
1. Configuration Settings
a. Make sure the volume is not turned down or the speakers muted. Open the Sound properties and check each setting for proper configuration. In addition, each audio application or player you use will have its own settings. Use a common audio file player when testing audio, such as Windows Media Player instead of itunes for example, and play files from the hard drive, not off the internet. The idea is to keep it as simple as possible in order to reduce potential configuration issues and problems with the applications themselves.
b. Check the default audio device setting and make sure it is set to your device (Sigmatel, IDT or Realtek) and not usb audio, HDMI, etc..
2. Use System Restore
Windows System Restore backs up certain system files (exe, dll, etc) and also backs up the Registry and many drivers. Sometimes reverting back to an earlier Restore Point can fix a "no audio" problem. Using System Restore will not delete any data files.
In XP, go to Start>All Programs>Accessories>System Tools>System Restore
and tick 'Restore my computer to an earlier time'. Choose a date before the problem first occurred.
In Vista and 7, type "System Restore" into the Start menu search box, and then, in the list of results, click System Restore.
3. Re-install the Audio Driver
a. Do a simple reinstall. Open the Device Manager and find the audio driver under Sound Controllers (it will be named Sigmatel, IDT, Realtec, or Crystal). Right click on it then click "uninstall" and do not select the option to delete the files. Restart the computer and Windows will reinstall the driver. The reason this process fixes some "no audio" problems is because it resets the driver configuration to its default settings.
b. Installl fresh driver files. Go to the Dell driver folder on the hard drive. The location is c:\dell\drivers\
Expand all folders and all subfolders there. Delete all folders that have a subfolder named "WDM". Those will be the audio driver folders and it is safe to delete them.
Next download a new audio driver package from your computer's driver downloads page. Go to the Driver & Downloads Home Page and follow the links to select your laptop model and its operating system. Expand the 'Audio' category and download the audio driver named Sigmatel, IDT, or Realtec. Do not download anything named "Creative Labs" at this time. Next, unzip the files and install the driver. When you unzip the files they will be unpacked by default to a new folder on the hard drive at c:\dell\drivers\Rxxxxxx -- similar to the one(s) you deleted except that it will have fresh files and it will be the newest version of the driver if you did not already have that.
II. Hardware Diagnostics
If the general steps did not help, do a diagnostic analysis of the computer to discover the problem area which is the cause of the symptom. Diagnosing "no audio" is a process of eliminating potential problem areas and eventually narrowing down to one problem area. These hardware tests can narrow the problem down to either the software or hardware. This is important to know because if the hardware is shot then no number of software solutions will fix the problem and will just just be a waste of time. When doing the tests do not use usb headphones or usb speakers.
a. Sense Pin Test. Connect headphones or external speakers to the output jack and listen for audio. The reason for this test is that if audio comes through the jack but not through the internal speakers, that is one of the symptoms of a failed sense pin in the jack which is a hardware problem that the audio tests in Dell Diagnostics will fail to detect, so you have to test for it specifically. If this test does produce audio from the jack but not the speakers then see the Headphone Jack FAQ to find out how to complete the diagnostic. Note however that the failed sense pin problem will only occur on Dell laptops with HD audio (all models built in the last 6 or 7 years), not the older models with the AC97 hardware codec.
b. Dell Diagnostics Audio Tests. These tests are designed to narrow the problem area down to either the hardware or software, and will detect the existence of any hardware failure except the failed sense pin mentioned above. If the computer cannot pass these tests then there is no need to attempt any software solutions. Do not confuse these tests with the PSA tests which will run first but will not definitively test the audio hardware. See the Dell Diagnostics Audio Tests FAQ for more details and instructions.
c. Original Factory Configuration. If the Dell Diagnostics audio tests cannot be run then an alternate test is to return the computer to its original factory configuration. This is usually done as a last resort solution, but it is also a diagnostic tool because if it does restore audio functioning then the problem area is the software, and if it does not restore audio functioning then the problem area is the hardware. To return the computer to its original factory configuration for diagnostic purposes, use PC Restore for XP, or Factory Image Restore for Vista and 7. The instructions are in the Owner's Manuals and Setup Guides.
Note that there are 2 problems that this will not correct: the bad sense pin mentioned above, or a problem with bad firmware on an optical drive or other device, because the firmware is stored on the device itself. The system BIOS is also firmware. However bad firmware on a device will not cause the "no audio" problem that is the subject of this faq.
III. Software Problems
If the laptop passes the hardware tests then logically the problem area is the software (except in the case of a bad sense pin).
1. Audio Driver
Often the driver is the cause of the audio problem. Re-install the driver as explained above. I have made a separate Audio Driver FAQ that is divided into 12 topics:
1. Basic Un-install & Re-installation
2. How to Find and Delete the Driver Files
3. Download a Fresh Copy of the Driver Files
4. Download an Older Version of the Driver
5. How to Fix a "File Not Found" Error When Downloading the Audio Driver
6. How to Install the Generic Audio Driver
7. How to Install the Audio Driver After Re-installing the Operating System
8. You Installed Windows 7 But Can't Find a 7 Version of Your HD Audio Driver
9. You Installed Windows 7 But Can't Find a 7 Version of Your AC97 Audio Driver
10. You Installed Windows Vista But Can't Find a Vista Version of Your AC97 Audio Driver
11. You Installed Windows XP But Can't Find an XP Version of Your Audio Driver
12. Crystal Drivers for Inspirons 8200 & 2650, Latitude C840, Precision M50 & Others
2. Windows Operating System Problems
a. Correct Order. If there is no audio after reinstalling Windows operating system it is usually because the drivers were not installed in the correct order. See Section 7 of the Audio Driver FAQ.
b. Audio Service. This has to be running to get any audio. Go to Start>Run and type "services.msc" (without quotes) then hit the 'Enter' key (or click 'ok'). The Services window will appear. Scroll down until you find "Windows Audio" towards the bottom of the list. Check that it is enabled, set to automatic, and running. If it isn't, double click on it and change the Startup type to Automatic, then click Start, Apply, and OK.
c. Automatic Updates. Windows Automatic Updates is a Microsoft service that runs in the background and installs security updates and other enhancements into your computer. Occasionally some of those changes result in a permanent state of "no audio" until Windows is re-installed. A way to avoid that potential problem is to have Automatic Updates set to "ask me" each time for permission to download or install any changes and then only allow security updates to be installed.
d. Viruses. Windows is vulnerable to viruses and malware. Run an anti-virus program and have it routinely scan for viruses. Keep the Windows firewall turned on. Keep the Microsoft security patches up to date.
Some additional things to look at particularly on older models.
1. Other Hardware Problems
a. Headphone Jack. As explained above, a jack can have a failure of the sense pin. However that is not the only possible jack problem -- particularly on older models that do not have a sense pin. See the Headphone Jack FAQ for more details and a list of the models that have replaceable jack circuit boards.
b. Modem. In some models the modem can have a problem that interferes with the the audio system. Symptoms include inability to get the audio driver to install, getting an error message saying no audio hardware present, and audio properties settings being grayed out. To test this you have to physically remove the modem, not just uninstall the driver. With the modem removed, try again to install the audio driver. If the audio works after removing the modem then you might need to replace it. This issue is more likely to occur on older models.
c. Loose or Broken Speaker Wires. A connection to the speakers can be loose, or on some models the connection to the palm rest which houses the speakers can become loose and cause the speakers to stop working but still allowing the headphone jack to work. Wires are more likely to come loose than to break, but in a few models like the Inspiron 700m & 710m where the wires are routed through the hinges, the wires can pinch during the opening & closing of the display screen and break. Often you can hear some audio through the speakers when the screen is partially closed as the frayed wire ends make contact. For more information on this problem see the Speaker Wires Break in 700m & 710m FAQ.
d. Speakers. The speakers themselves can stop working. This is somewhat rare but not unheard of. If you hear the test tones when you run the PSA tests then the speakers work. See the Dell Diagnostics Audio Tests FAQ for more about the PSA tests.
2. Other Software Problems
a. Windows Audio Endpoint Builder. If you try to start Windows Audio Service and get an error message about the Audio Endpoint Builder, it may because of a failed installtion of the Creative Labs software that can be downloaded from the driver pages of some of the laptop models. This software has several names, similar to "Integrated Sound Blaster Audigy Advanced HD Audio". The software should be removed but that alone will not solve the problem. Create a System Restore point, then Go to Start>Run and type regedit to open the Registry editor. Navigate to
and in the DependOnService line remove all entries except RpcSs [double click on the line DependOnService to open the edit box for that line] and then restart the computer.
b. Software Device Enumerator. If you get a message like "no audio device detected" or "driver is enabled but has not been started", go into the Device Manager and check that 'Plug and Play Software Device Enumerator' is installed and running. It will be listed alphabetically if there.