Try shutting Word Chums down completely and then restart it. To shut it down go to any home screen on your device (a screen where you see all your app icons). Double tap the home button on the front of device.
In iOS 7:
You can swipe left and right until you see Word Chums. Then swipe UP on the Word Chums "card".
In iOS 5 and 6:
You should see a row of apps at bottom of screen. Assuming Word Chums is one of those...tap and hold Word Chums until the apps wiggle and you see a minus sign. Then tap on the minus sign on Word Chums to shut it down.
Now try to open Word Chums again and see if it works.
If it repeatedly freezes up or the same action causes it to freeze or crash every time go ahead and send a note to support.