Hi,
Thank you for sharing your question. I know how annoying it is when your USB-C headphones suddenly stop working on your computer, mostly when they were working before and still work on other devices.
Usually, this happens because of old or messed-up drivers, disabled USB ports, or audio setting problems. To fix it, first, see if the headphones show up in Device Manager under Sound, video and game controllers or Universal Serial Bus controllers. If they do, right-click and choose Update driver. If not, try unplugging and plugging the headphones back in, then restart your PC. You could try running the Hardware and Devices troubleshooter by typing msdt.exe -id DeviceDiagnostic in the Run box. Also, make sure your audio input/output settings in Settings → System → Sound are set to the right device. If it's still not working, reinstall the USB controller drivers or update Windows.
I hope this helps.
Best Regards,
Noel