One of my loudspeakers is not playing any sound?

The polarity may be reversed for this speaker. To test this, swap the two wires (positive “+” and negative “-“) in the speaker connector.

Uninstall the speaker from its mount. Take the wire that was connected to the positive terminal and connect it to the negative. Likewise, take the wire that was connected to negative and put it onto the positive terminal.

If the speaker starts playing correctly, secure the wire connections and reinstall the speaker into its mount.