It does not matter how the sliders are set as long as they are both the same dB level. If you want to double check that, open the Playback tab of the Sound properties, right click on Speaker/Headphones, select Properties, select the Levels tab, click the Balance button. The point of a simple re-installation of the audio driver (no downloading) is that your settings will be lost - in other words the default configuration is restored thereby ruling out a configuration issue, such as being set to mono in the Sound properties. You don't need to do it because you tried the native driver which served the same purpose. I did not uninstall the driver and downloaded a fresh one because it would seem odd to be the issue, after working for 3 years and all of a sudden it stops. But no point in doing that if only one speaker is heard in the previous test. If it is a software issue then the recovery will fix the problem, and if it is hardware then it won't and hardware will be confirmed as the source of the problem. The final test you can do is to perform a system recovery. If you only hear tones through one speaker then the other speaker is confirmed to have failed or has a loose connection.

If you hear tones through both speakers during the tests then the speaker itself is all right and some other part is the cause of the problem, probably the headphone jack since you know the audio is working correctly up to that point. If you don't have it then just fail the color bar test as described in the FAQ. Note that not all models have ePSA and not all ePSA have Quick Audio check.

Another test you can run is the ePSA Quick Audio Check.

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