If your Raspberry Pi isn't outputting any sound, here's a list of things to try which usually resolve 99% of sound issue queries:
- Audio Source - Have you selected the audio source from the Raspberry Pi OS desktop? There's an audio icon you can select (right-click) to choose the audio output device.
- Raspberry Pi OS - Are you using a recent copy of the Raspberry Pi OS? The sound software and drivers were recently changed over to PulseAudio (Dec 2020) which has brought some vast improvements. This is a good troubleshooting step to confirm it's not the image or old software causing the issue - and sometimes simply reinstalling the Raspberry Pi OS fixes these issues too.
- HDMI Port - Are you plugging your HDMI cable into the left micro-HDMI port labelled 'HDMI0'? This has to be used when using only one screen.
- TV Audio Mode - Sometimes a computer monitor or TV reports its preferred mode incorrectly, and this can occasionally be a mode which can't pass audio. To correct this, try editing the config.txt file on your micro-SD card and adding the following line: hdmi_drive=2
- Video Adapters - Some adapters (HDMI to VGA/DVI etc) don't pass sound via the main cable, so you may need to route the audio separately via the adapter using an audio cable. You still need to select HDMI audio in most cases, to send the sound via HDMI to the adapter.