The laptop has unexpectedly crashed; some drivers, such as the one for the keyboard, are corrupted. I cannot reinstall them without a keyboard. Alas. I did manage to back up my Stuff, so it is more of a tremendous inconvenience and annoyance than anything else. Nevertheless, it is also one of the increasingly numerous metaphorical ducks that are pecking ever relentlessly with their dull beaks.
I will see what can be done about the computer in due course.