You are making it sound as though you have no sound whatsover on the iPad which could mean that the device is defective. Lets assume that is not the case right now - and Please do not be offended - even if you are quite a "techy" - I just want to cover the basics again.
If you can play music and have sound in videos - maybe you have system sounds muted. Read this.
If you lose sounds for keyboard clicks, games or other apps, email notifications and other notifications, system sounds have been muted.
System sounds can be muted and controlled two different ways. The screen lock rotation can be controlled in the same manner as well.
Settings>General>Use Side Switch to: Mute System sounds. If this option is selected, the switch on the side of the iPad above the volume rocker will mute system sounds.
If you choose Lock Screen Rotation, then the switch locks the screen. If the screen is locked, you will see a lock icon in the upper right corner next to the battery indicator gauge.
If you have the side switch set to lock screen rotation then the system sound control is in the task bar. Double tap the home button and in the task bar at the bottom, swipe all the way to the right. The speaker icon is all the way to the left. Tap on it and system sounds will return.
If you have the side switch set to mute system sounds, then the screen lock rotation can be accessed via the task bar in the same manner as described above.
This support article from Apple explains how the side switch works.
Make sure that you have the sound turned up using the volume rocker on the right side of the iPad as well. The volume rocker is right below the side switch.
Demo covered more than I knew about sound levels! Regardless, I do not think a brand new iPad would have the sound turned off. The only way I can see that it got turned off was in the process of syncing with iTunes and transferring some iPhone App data to it.
The only other thing I can think of to try, is to reset (reboot) the iPad. This might correct something in the iPad's OS that was corrupted. Hold both the Home and Sleep buttons for several seconds until the Apple logo appears. Ignore the "Slide to power off" arrow. The iPad will restart after a couple of minutes. Resetting this way will not hurt anything, and sometimes clears up mysterious problems.
I suppose some stores will replace an iPad that is defective out-of-the-box. Otherwise you will need to take it to an Apple Store Genius. There you may get a new iPad on the spot.
Message was edited by: Fred*M.