Just got my iPad 2 yesterday, love it. However, I downloaded the ABC, Real Racing 2, and Flight Control apps. I made sure my volume and ringer was turned all the way up, but still no sound.
make sure that your rocker switch is not set to mute.
It's not, I have that set to control rotation.
Edit: I went in settings, set it to control sound, muted it and un-muted it and it fixed it. Thanks for the help.
I had the same issue, then a buddy of mine asked if the rocker switch was muted and of course it wasn't but get this I had the rocker switch set to rotation lock my buddy set it switch to mute and then launched the an app " angry birds" and no sound..... Then while in the app switched to unmute and bam sound!!!!
I believe that some apps confuse the rotation lock on as mute, since then I haven't used rotation lock and all is good!
This worked perfect for fixing my problem too