Hi @DissipatedHarry! Could you try these steps and see if it fixes:
1. Logout from the site, then login again
2. On Themes, hit the 1st one then on Sound pick a different one, confirm, then pick Default again and confirm, play a game to see if it fixes. (assuming you're using Default)
Please let me know in case you've tried these and it's still not working.
Thanks for the reply - I really appreciate that. Unfortunately, I have tried these steps and it still doesn't work.
Thank you for the feedback @DissipatedHarry as a last resort, could you try clearing your browser cache/cookies?
In case it still doesn't work, please do reach out to our Support team at https://www.chess.com/support where a specialized team member will be in touch directly with you to make sure that this is fixed!
Sorry for your trouble, hope that we can get it sorted out soon! 
Hi,
I play 1+1 games to (try to) prevent cheating but last week my move sounds disappeared which adds a level of challenge to such games I am probably not equal to. My other sounds are fine, as are my speakers. I have tried unplugging speakers, refreshing browsers, restarting PC and checking all the appropriate settings are enabled after toggling them.
I have searched on this but haven't seen an answer to this elsewhere. It would be great to get an answer as I don't really want to switch to lichess.
Thanks