This issue may show up after a Windows Update, or headphones may just stop working on a specific device but continue to work on others. When a Windows Update has triggered the issue, it may be because updates for several components of a computer are engineered to fix problems, but unfortunately those updates may result in breaking other components. That is usually caused by the incompatiblity of the operating system and drivers. Here are some suggestions for fixing that situation:
Manually set Headphones as the default device.
For this quick solution simply go to Start> right-click System > Sound >Output
Select Headphones to get the sound working again.
Update or rollback your Audio & Bluetooth drivers.
If an update is recent, you can roll back one of more drivers to older an version that works as it did prior to recent changes made to the system. If there was no update, it is possible that the drivers still need to be updated to the latest version(s). For your Lenovo product use Vantage or manually go to Support for your language/country and follow the prompts for entering your device information. English is here: https://support.lenovo.com/us/en/ When you arrive at the driver download page check dates for the following drivers to see if your system is running one or more outdated drivers. If so, update:
Sound, video, and game controllers.
Use the Audio Troubleshooter.
To use the Windows 10 Audio Troubleshooter, from Start open Windows Settings. Go to Update & Security > Troubleshoot.
Select the option called Playing Audio.
Click the button called Run the Troubleshooter.
Follow the on-screen instructions to see if this fixes your issue.
Lastly, if nothing has helped, you have the option of uninstalling the last Windows Update by going to Start>Settings > Update and Security > Windows Update > View update history. Click on Uninstall Updates.
There is a chance that an update has been released or will be released soon to repair your problem as millions of other users may have reported it via The Feedback Hub.
It always helps if you report the problem yourself as well. Therefore, as Microsoft hears from more users a future update/patch may be in the works.