Does Tools>Check Media report any files as missing? If you drag an mp3 file onto mpv.exe in Anki’s program folder, does it play? If not, what does it say?
I ran ‘check media’ Mp3 files are not missing, also they are present in media folder where anki stores media. Here is the attachment:
I dragged the mp3 file into mpv player, it ran fine through that too.
What’s surprising is, now all audio files are running fine, both in preview and review screen!
I think Check media does something as a fix?!
But in all this process, i found an another bug, audio doesn’t stop after closing the preview screen[It continues to run after closing preview screen & stops only after its runtime]
About the original issue, if it happens again, try to close Anki and create mpv.conf in %APPDATA%\Anki2 with autoload-files=no option to prevent automatically loading external audio or subtitle files, or download it as zip from this gist.
The %APPDATA%\Anki2 folder can be opened, for example, by clicking and editing the address bar in Windows Explorer or using Win+R or Win+S (or Win) shortcuts and pasting %APPDATA%\Anki2.
Something similar happened to me yesterday and again today. In my case, after restarting Windows and opening Anki, it could take about a minute to hear the sound for the first time, probably due to the collection.media folder containing a lot of files, slow HDD speed and high disk usage by external apps. But once it happens, the auduo seems to work fine for every new card or after restarting Anki.