After having my kettle blow a fuse, the next day my laptop computer packed up. The enigmatic message "Unknown Hard Error" came up and I could do nothing but turn off the power. When I switched on again all I could get was a blank screen with cursor at the top left. Apparently the fault was in the mother-board. I ended up paying £150for a replacement, reconditioned, computer.
Fortunately I had kept a back-up of most files on a USB stick, and it also proved possible to save the most recent work from the hard disk, so I don't think anything significant was lost. I prefer to use a separate laptop for most of my wordprocessing, rather than the PC that I use for connection to the internet.
As reported earlier I've been making progress in sorting out all my files on knight's tours, with a view to publishing the results in book form. I've also rediscovered a lot of other work on geometry and numbers and puzzles that I'd half forgotten. This could form the basis for several books, if I can find the energy and motivation to complete them.