Just what I wanted, thanks.
Jackie
Thank you for contacting me.
Since I posted this I did some further investigation. I thought why would there have been two updates of the same version and if something had gone wrong I would expect things not to work and not just to revert to a previous date.
That made me think perhaps something had happened with my host, so I contacted them. I discovered that in their infinite wisdom they had done a hardware upgrade and moved to a new data centre without directly informing their clients. So the data lost was due to my provider and not WordPress.
So my initial panic and lack of faith in WP was proved incorrect.
Thanks again.
