I have had this problem for a while now. My Speakers dont put out any sound. But the Headphones jack do! I have somehow found a solution to the problem and wanted to share this with the Community. I recorded a video where I show how to fix it. Maybe this will help you!
See the YouTube link below...
More Info that helped me:
Does not work for me. I followed your procedure but nothing worked.
Compared to yours, my audio ONLY works if the Speakers / Headphones is selected as the default device, not the Independent RTC Headphones. If I force my microphone array (like the on in your video) to output to the RTC Headphones, the bar on the side detects some sound but does not output it to my headphones. Also, with Speakers / Headphones set as default, I can only hear audio through my headphones, not my speakers. There's no problem with my speakers because if I use default Microsoft audio drivers, then they work (though I do need to set default device to whichever one I need, the speakers or headphones).
Youtube solution oes not work on my 1645 xps studio, but i did get sound working by un-installing IDT then sawp the default speaker in Sounds> Playback. HTH
PS. so many users are having this trouble i am not convinced its a faulty hardware issue. I reckon it may be sloppy software, cmon Dell, FIX IT PLEASE!!!!!!
I suddenly started having the same symptoms with Dell Latitude 6400 running Windows 7. For me, it was simply a case of restarting the Windows Audio Service. Now I am getting sound from my speakers again.