No sound on your computer is usually caused by one of these: the volume is muted (check the taskbar volume icon and keyboard mute key), the wrong output device is selected (especially after plugging in HDMI or Bluetooth), or audio drivers have crashed. Start by clicking the volume icon and making sure it's not muted and the correct output device is selected. Try playing audio from different apps to determine if it's system-wide or app-specific. On Windows, right-click the speaker icon > Troubleshoot sound problems to run the automated fixer. Check Device Manager > Sound, video and game controllers for driver warnings. On Mac, go to System Settings > Sound > Output and verify the right device is chosen. If sound stopped after an update, update or roll back your audio driver. As a quick fix, restart the audio service: on Windows run "net stop AudioSrv && net start AudioSrv" from Command Prompt; on Mac run "sudo killall coreaudiod" from Terminal.