There are a couple of things you can do to check and fix sound effects issues.

1. Check the game settings to make sure sounds and music are turned on.
2. If all the settings are on and the sound effects/music is still off, try restarting the game app.
3. If that doesn't work then you can try restarting your device.

This will normally fix the issue but if that hasn't worked then:

1. Make sure your device is not muted and that the volume is turned up high enough.
2. If you have headphones connected try plugging them in and out.
3. Make sure your music player is turned off.

If none of these steps worked for you then open another application to make sure your sound is working in general. If the problem persists, then it may have something to do with your device itself rather than the game.