The problem can be the computer settings or the monitor in built speakers.so to confirm the fault first connect the external speakers to your computers mother board .by computers mother board i mean the mother of the CPU in your system. connect the speakers and check.if there is no sound then its the problem of the settings in your computer .either the sound settings is got muted or the sound card is got faulty or the sound drivers have got corrupted. but if you hear a sound from the external speakers then its the fault in the monitors in-built speakers .in this case the you will have to check the sound cables in your monitor. there should be an input (generally on the underside) it is usually green. There should have been a cable included (double male) that would plug in to the monitor input and then to your tower input, which is generally also green, this has to be hooked up in order for you to have sound. the color of the cable may differ in some cases. There should be a small cable running from the computer to the monitor for sound besides the heavy video and power cables. Make sure it is plugged into both ends securely. it is possible the power supply built into the monitor has failed also. You can buy replacement speakers for 10 dollars or so and plug them into the audio out port on your computer. If that still doesn't play then you either have corrupted audio drivers or defective hardware inside the computer. This will help. Thanks please keep updated.please do rate the solution positively .thank you for using fixya