Quick check: Run the related device test and keep it open while trying these steps.
Test at a safe volume
Turn the device volume down before opening the speaker test. Play Center first, then Left and Right. If Center works but one side does not, inspect the cable, headset balance and speaker connection. If nothing plays, the problem may be output selection rather than a broken speaker.
Select the intended output
Open Windows Settings → System → Sound → Output and choose your speakers or headset. A monitor, capture card, controller or Bluetooth device can unexpectedly become the default output. Look at the Windows volume mixer as well: an individual browser can be muted while other applications still make sound. Check the tab’s mute control in the browser.
Separate browser from system trouble
Try a familiar audio file in a different app. If it also fails, reconnect the audio cable or Bluetooth headset and use Windows’ audio troubleshooter. If only the browser is quiet, check the browser’s per-app mixer level and restart its tab. If only one website is quiet, check that page’s player volume or mute button.
Understand what a channel test proves
A left/right tone checks basic routing, not audio fidelity, frequency response, delay or microphone monitoring. Stereo effects, virtual surround and some accessibility settings can change what each channel sounds like. Test with such processing disabled if you need a simple left/right check, then restore your preferred settings.
After each change, test the device again. Change one setting at a time so you can identify what helped.
Further reference: Official device or browser documentation ↗