No Sound Through Headphones

Hello! I've already read through many of the similar questions on this forum, however none of the solutions seem to work.
Sound comes through perfectly fine on my laptop's built-in speakers. However, when plugging my headphones into the 3.5mm headset jack, there is no sound whatsoever. The system recognizes that my headset is plugged in. In fact, the microphone on my headset functions perfectly when plugged in, but the headphones themselves are outputting no sound.
I tested the headphones on other computers and devices, and they work.
In Device Manager, the device is listed as "Realtek High Definition Audio". However, the only sound device listed in Control Panel is "DTS Audio Control Panel".
I've tried uninstalling the audio device from Device Manager, and then reinstalling the driver from Realtek's website.
However, this is met with the exact same results... no sound through the headphones, and "DTS Audio Manager" is installed in the Control Panel instead of Realtek HD Audio Manager.
If I navigate to Control Panel -> Sound -> Playback, "Headphones" is not listed as a device. Instead, Speakers/Headphones is listen as the sole device.
Also, I ran DirectX Diagnostic Tool, and it returned absolutely no errors.
I have posted screenshots and a few of my system specifications just in case.
Thank You!
Model: HP ZBook 17 G2
OS: Windows 10 Pro 64-bit

The DTS is an enhancement to the basic sound (Realtek).

SOME PC audio jacks are combination mic OR headset but not both at the same time. Other Laptops have separate jacks for the headset and mic and finally some new laptops have a combination jack but it requires a 4 connector plug, like is used with iPhones for both the headset and mic to work. Then again, if your mic/headset uses a 4 connector plug but the PC requires the standard 3 connection (TRS) jack that could be the problem.

I would try a different realtek driver as mine is separate. When I plug in the headphones, it automatically switches to the headphones as the default sound device. I'm currently using a usb external sound card though.

I get no sound from external speakers, whether headphone jack or USB type. The USB speaker shows in Device Manager but the headphone jack one does not.

Both speakers test fine in other laptops running Windows 7.

I've sorta solved the problem by ticking Loudness Equalisation in the internal speakers' Properties>Enhancements, so I no longer need an external speaker. Must get around to phoning Dell but the last time I did the so-called M3800 specialist was clueless.