Problem:

Your Firefox suddenly does not play any sounds.

You have tried uninstalling and reinstalling it but the problem still persists.

Quick Solution:

1. Go to Windows Settings > Sound > Advanced Sound Options .
2. Make sure Firefox is not muted or set to low volume.

Advanced Solution:

1. Create a Firefox account and synchronize (make a backup of) your current settings.
2. Uninstall Firefox using Windows Apps and features.
3. Go to %APPDATA%\Mozilla and delete Firefox folder.
4. Open regedit.exe, search for Firefox, and delete all the keys and values that can be found. This process will take some time. Just ignore any errors that may occur when some keys or values cannot be deleted.
5. Restart your computer.
6. Download Firefox offline installer.
7. Install Firefox.
8. Log in your Firefox account and restore your settings.