No audio as soon as I remove jack from the audio port. If I reinstall the sound card driver, speakers work fine but if I use headphone jack then the problem reoccurs.

It has been persistent problem because my motherboard was replaced and on both the motherboard this problem existed.  

Like the ethernet port which is shows no link even when the drivers are up to date and hardware diagnostics says no error on the hardware but no connection. Tried various wires, several places, home office and its the same...

the driver provided by DELL never worked

Hello. In what way is the driver not working right?

they never fixed this problem.

What is the nature of the problem -- no audio, or something else?

Until Windows 8 it was all good. All mesh started with Windows 10 even though DELL claims that its fully upgradable to WINDOWS 10. I have found another driver that works perfectly well and its not from IDT but another company that makes custom driver for same chipset the one I have in my laptop. It fixes the bug and have no problem. I want to raise awareness that there are many bugs in the drivers posted by DELL which dont seem to work.  

Did the laptop have this problem in its previous operating system, before Win10?

Your model has IDT audio hardware. Test it by switching from the IDT driver to the Windows native audio driver.

1. Open the Device Manager (find it in the Control Panel, or type devmgmt.msc into the search box).

2. Expand the "Sound, video & game controllers" and right click on "IDT High Definition Audio Codec".

3. Select to "Update Driver Software".

4. Click on "Browse my computer for driver software".

5. Click "Let me pick from a list of drivers on my computer".

6. Put a check in the box "Show compatible hardware" if not already checked.

7. In the list of devices, click "High Definition Audio" (the native driver).

8. Click "Next".

9. On the Update Driver Warning box, click "Yes" (install the driver).

10. Restart the laptop if prompted. If not prompted, then no need to restart.

[To get back to the IDT driver, do it again but reverse the names in steps 2 and 7.]

If it works all right with the native driver then probably there is a problem with the Win10 IDT audio driver. I would remove that driver from the system, then install it again but use compatibility mode while installing, and select compatibility for the previous operating system. I doubt that there is an actual Win10 IDT audio driver because that company is no longer in the consumer audio business. I suspect that Dell just relabeled the existing Win7/8 driver as being for 10.

If you have the same problem with both the native driver and the Realtek driver then there could be a hardware failure -- where the sensor in the jack is failing to detect when the headphone plug is removed, so the audio fails to be switched back to the speakers.

I'm pretty sure that Dell made a mistake in saying that the IDT audio driver is for Win10. That driver was issued a couple of years before there ever was a Win10, so it definitely was not written for 10.

If you want to be helpful you should post the solution that you have found.