Try resetting it.
Press and hold the Sleep/Wake button and the Home button at the same time for 10-20 secs until the Apple logo appears on the screen. The iPad will then reset and restart
Thanks Milvus - the happy pixie (sorry, my husband) did that and it works now. Just don't know why the stupid thing turned itself off in the first place (it is a cool toy but it is too complicated for me).