There should be a "level" or "volume" control on the subwoofer. It sounds like yours may have been accidentally turned-down. Before adjusting that volume control on the subwoofer, REMOVE THE BASS BOOST YOU ADDED IN THE AVR... that's critical to avoid damaging the subwoofer. Next. lower the volume level of the AVR so that it's not off, but is at a low level that won't blast the sub when you start sending a test or music signal. Adjust the subwoofer volume control to get the sub to the right output level and you should be back to normal. I've heard of cats rubbing against the warm amps and turning the volume potentiometer (pot) way up or way down. Dogs and toddlers have also been known to move the volume setting.