Welcome to the Candy Crush Saga Community
Do you have a question or need help with your game? Ask the Community.
Hey Lucy. Here are a few things to try. Firstly you need to make sure that your device meets the following:
iOS version 6.0 or later on the following models:iPhone 4S, iPhone 5, iPhone 5s, iPhone 6 and later models.iPad 2 and later models.iPad Mini.iPod Touch 4th generation and later.
Force close all apps and restart your device: http://support.apple.com/en-us/HT201559
Finally if that does not work then check that you have the latest version of Candy Crush installed, enough spare memory and restart the device after you have installed the app. Make sure that your progress is backed up with Facebook or the Kingdom or you will lose your levels after a re-install.
Let me know how you get on :-)