It looks like you are visiting outside the United States of America. Please visit your local website.
Please check the following points:
1) The power indicator light should be ON
2) Try to turn up the volume
3) Make sure the audio cables are correctly connected
4) Make sure you set the input correctly on the speakers
5) The audio source should deliver a signal output
It's a pair.
These are not powered Edifier speakers so you need a receiver or amplifier to do so.