Thanks once again for replying Roy. I appreciate that.
The sentence about a scan not being available on all screens was an ill thought through one on my part. Enough to say that scan is always available in the Snipping Tool screen.
I tried the SFC and the result was no integrity violations, so that's o.k.
As regards the repair install, do you mean going to the tablet options box, unchecking, rebooting and then checking the box again to reinstall ? If so, I have done that. Are you perhaps talking about another way ?
It is curious that the only part of Snipping Tool not to respond is the email request. I have no other mail problems, so something is blocking the initiation of that click request to email. The only other wild card solution I can think of is that I installed Avast in place of AVG, but I can't imagine that I would have not had associated problems if Avast were to be the cause.
Anyway, I will understand if we have come to the end of the road here. I know absolutely nothing about computers, and have only gone into this because, likely enough, it's something blindingly simple which is hiding itself extraordinarily well. This is rather annoying. Never mind. Thanks.