Unable to attach extenal speakers to HP laptop

In that same window showing speakers with the green checkmark right click any empty space in that window and select Show Disabled Devices. Is your headphones listed?

To rule out a hardware problem you could boot a live linux distro off a USB flash drive and see if you get sound through the headphones. That would at least rule out a hardware problem.

Mint Cinnamon is a good distro for a test.

Looks like we've been barking up the wrong tree.

If the Sound-bar works fine on another laptop but not on the laptop concerned, and the headphone jack is not producing a signal on that laptop either.

Question: Does the affected laptop produce sound through it's normal speakers?

Solved! After some troubleshooting with an HP tech, he discovered that the switch in the Settings > Sound that "allowed" sound output through the headphone jack had never been switched ON. Once done, everything going through that port worked... soundbar, speakers, and headphones, too. Somehow I always believed that my problem was some simple setting needed to be changed, just that I never found where it was.

At any rate, good folks, this experience has taught me yet something else I had not yet learned. Sorry I couldn't have been more helpful, but my tech-savvy just wasn't there. My thanks to all of you who took the time to get involved.

Hopefully this information will benefit someone else.

Glad you got it solved and thanks for taking the time to post an update.