Why has my calendar stopped working?

[Diannet4]

calendar stopped working

I keep getting on screen message saying unfortunately calendar storage has stopped can anyone please tell me why.

 

[B. Diddy]

Re: calendar stopped working

Welcome to Android Central! What phone do you have? Have you tried rebooting? That is, powering the phone completely down, then turning it on again? (Not just putting the screen to sleep.)