Well a factory reset seemed the only option. However, it's damn near given me heart failure especially when it all started up in Chinese or some similar script. Thanks be to the internet for showing me where I needed to click to get English back up and running. It's still no-where right though, I just hope one or more of these back-up routines will put things right - I have tried Helium, but I don't know if it worked. It says that the Edge screen is on, but I seem to have lost the little widget which opened things in it - I used to roll over it and it opened the edge screens. Also all the icons seem bigger and further apart so I've lost something there (Edit - edge screen and edge icon placement were both solved in settings - easy mode - switching it off!), I also can't find the icon to open the Google Play store (edit - have just spotted it) - all ideas as to where all these things are hiding would be welcome folks. At the moment some sort of restore of data appears to be occurring from somewhere - heaven knows what's kicked in, but I'm doing some sort of cross everything routine at the moment that something good is happening.
The big warning here folks, is although it might solve my calendar issue, you click the big factory reset button at your peril folks. It nearly had me in tears at one point.
Edit - restored a load of apps from Google account, have restored wallpaper - it looks like mine again LOL - nearly back to normal after 2 hours of worry - just got to set up things like email accounts again, but these are all replicated elsewhere so I'm not losing data - the phone is just email on the go. So the upshot is that it looks like you can revive from a factory re-set, but you need to have the courage of your convictions and if you have a grey import find out how to change from Chinese (or similar) language before you press the magic button, as when it boots and does the initial set-up stuff, its all in Chinese and you are left guessing. Link here for a You Tube video of what to press - stop it when you need to and look at your screen.
https://www.youtube.com/watch?v=mfLQ7FyeBjA
NB. On the plus side the wretched Calendar stopped message looks like it has finally gone away.
