Turn mute on/off

http://usa.yamaha.com/products/audio-visual/speaker-systems/subwoofers/yst-sw215_piano__u

If you hold the power button down a menu pops up - the last option is for mute/unmute. Make sure this is not set to mute.
If this doesn't help, it could be that some app you are running is muting the sound. Close all apps and see if that helps. Power off/on and see if that helps. If you do determine it is an app that's causing the problem, add a comment about it in the Play Store so the developers will know and hopefully fix it.

There should be a button on the front that says omething like multi-channel in. Press this to turn off the multi channel function.

Use your computer speaker as the sound device or use a headphones.

If it sounds good, it could just be your cable that goes to the receiver.

( using a Y cable to connect to one of the regular audio inputs.)

or have one like these:

3.5MM To Stereo Rca Cables: Electronics

From the remote control only: Press MUTING to turn off the sound through all speakers and headphones connected. "MUTE" appears on the display and the volume turns off. To restore the sound, press MUTING again. Turning MASTER VOLUME or pressing VOLUME +/- also restores the sound.

Hi, It sounds like you are listening F.M. radio and the F.M. muting button is engaged ( as well it should be-otherwise you will have static between the stations ) sometimes there is almost a "THUMP" sound when you switch stations-this is caused by the receivers P.L.L. circuitry losing then locking in on stations, if you do not lower the system volume you will amost assuredly cause an overload of your final drivers, that's why it will come back on when turned off-it has reset. Turning off fm muting will get rid of the "POPPING" noise-it will however leave you with unbearable static which in turn should cause you to lower volume momentarily eliminating the need to constantly turn off the receiver. Thank for asking FixYa, I hope this helps, let me know how I did or if I can be of more assistance, good luck Prodzilla

So it doesn't actually play anything, right.

Name the model for our benefit. Tell us if you've referred to the manual. Define the related sources or outputs and what you have done that works or not.

Did it EVER work?

Look for a misplaced Mute or Tape Monitor control or Multichannel Analog Input selected.

There is a good chance that a common control may have developed a high-resistance or 'dead' spot through idleness and is causing your symptom. Turn the POWER OFF and operate every control throughout its range a number of times, especially rarely-used ones like Tape Monitors and the Mute control.

Turn the volume to something reasonable and see if that helped.

I can't find a manual either. Can I assume you really mean the sound is muted for EVERY source, not just tuner and CD?

I'd guess it's either MUTED or a Tape Monitor is active. Turn the volume down, select FM as the source, tune a station and use it as your test source. Look around for indicators that give a clue.

NEVER troubleshoot anything with the volume control turned way up. You'll blow up or damage the speakers and your hearing right after you discover and correct the misplaced control.

are you running the audio through an amp?? if so, it sounds like you are using the antenna remote wire(solid blue) instead of the amp remote wire (blue/white stripe) to turn the amp on. when listening to cds the antenna remote turns off.

Go to your sound and audio in your control panel.
Check to make sure your sound is not on "Mute" and also make sure the volume is turned up.
if it's not on mute or the volume is not turned downand you still have no sound go into the "Advanced" settings and make sure all levels are on the highest settings.