[Android Central Question]

I set up my Home screen with the most common apps that I use and the home screen works as it should - fine.
But RECENTLY (didn't use to happen before) IF I restart my phone OR if the phone runs out of battery and shuts down, when I eventually charge it up and re-start it, the phone looses the Home screen format with the apps I originally chose and create its OWN home screen "default" with just the basic Phone, Messages, and Camera Apps...
Why has it started doing this? I've had the phone 16 months and this never happened before - I don't understand why it suddenly started doing this?
Can anyone help?