The most common cause of this type of problem is the mute button, so this should be an easy fix. Please make sure that the MUTE button on the side of your device is off (if you see orange, that means that the device is muted and needs to be switched off).
Sometimes it helps to restart your device to get the sound working again. Also, on iPads, it’s important to make sure that the side switch is set to control Mute and not Screen Lock. You can check in your iPad’s Settings > Use Side Switch to > and make sure that Mute is checked.
If any none of those steps fixed the problem, please contact your team using the support form.