Why can't I hear sound when speaker at 100%

@terin21052 first try a set of headphones and see if those work. If so, insert and remove the plug a couple of times since it is possible that the headphone jack is stuck and does not open the circuit to allow the sound to be played by the speakers.

If that does not work you do want to go ahead and delete your current Audio driver and then reinstall the latest one for your computer and your OS (you have not told us your exact model nor what OS you are using, so we can't help you with that).

If none of the above works then the issue could be related to a component failure on the audio circuitry/audio amplifier, or the speakers itself. That would make it a motherboard repair and for that we will need to know your exact motherboard model number.