For sound problems please check that:

1. Your other applications have sound.
2. The mute switch of your device is off (some apps may disregard this switch, so they have sound even if it's on)

If the game crashes or sound problems continue:

First: close any open applications!

When you quit an app, it is not closed, even if you restart your device.
So sometimes you have a lot of apps in a waiting state... and they consume memory.

Follow these steps to force an app to close (see screenshot ):

1. From the Home screen, click the Home button twice.
2. Tap and hold on the app.
3. When it starts to jiggle, tap the to close it.
4. Double-click the Home button

If it still doesn’t work:

1. Restart your device
2. As a last resort, delete the application and re-install it.