Logitech USB Headset H390 now has no sound coming out after months of it working ok

You didn't downgrade at all. You'll need to confirm your headset has Windows 7 support and install the Win 7 driver.

Is this what you are looking for?

GENERALLY... ONE jack goes to AUDIO or SPEAKER... the second goes to MIC INPUT or something similar...

SO ONLY ONEjack should give you AUDIO from your headset is your MIC !

THIS Link MAY help you! "I" had to convert it to English ! Thank you "Chrome". At least you can glean some HELP telephone numbers...

https://www.logitech.com/assets/46742/3/usb-headset-h390.pdf

Dear angelqueenof,
May I ask you to use a spare headphones connected to the same source audio plug to verify if the issue comes from the source or from the Logitech ClearChat headset.
Regards,
Eddie Knight

You can buy replacement dongles from Logitech. Don't listen to lawrenceguo

Try it in another pc, you will see (or more precisely not hear) the most likely fact that the headphone's cable has quit. Buy a new pair.

I personally owned this item, they were great until an inadvertant accident just slightly extended its coord a few days ago, greatly destroying all sound effects other than music. All you have to do to get yours to play sound out of the headset is go into the control panel option. from there, go to Sound. You will find that there are your speakers and your headset if plugged in. All you have to do is right click the headset icon and choose the option "Set as default device" or something to that nature. To be sure they are working properly, right click the icon again and hit the "Test" button, you should hear two jingles, each coming out of a distinguishable earphone. If you find your programs or internet pages not playing sound through your headset at first, simply close them and re-open them. I had the same problem and am now actively searching for my own 2nd pair to replace my poor broken ones =(. I hope my post helped you solve your problem. =)

I've had this happen twice with Logitech headsets and believe it has to do with the cheap/fine wire they use in the cables. I suspect that a good tug on the cable will snap the wire or some other internal connection.

try on another pc in sound recorder if working there then the headset is not the problem. try uninstalling the sound card and rebooting the pc.
may correct the issue.