This morning I've noticed all my entries in my calendar, notes and contacts have disappeared from my ipad mini although they're still on my iphone. What has happened and how can I correct it, please?
If you use iCloud to sync them check that iCloud was not disabled on your iPad Mini. Go to Settings, iCloud and check that it is logged in with your Apple ID/iCloud Account. If it's not log in to the same account that is logged in on the iPhone and enable all the things (Calendar, Notes, etc) give it a while and they should sync back to the Mini.