Well here’s a thing. Yesterday there were a couple of brief power outages, both under a second, separated by an hour or two. The first did no harm other than causing routers etc. to reset and clearing clocks without battery backup.
The second did a little more – my desktop PC is protected against power surges, but the power interruption caused the computer to reset. It booted, but came up with a blank screen rather than my usual “which operating system would you like just now?” Grub boot screen. Um …..
I thought initially that maybe Grub had somehow become corrupt. Using Gparted I was able to see that all my partitions on all the drives appeared to be OK, so I tried reinstalling Grub. That seemingly worked OK, but the initial boot result was the same.
It then dawned on me that perhaps the cause wasn’t on the boot hard drive, but on the motherboard. During boot I looked at the boot options, and found that the hard drive boot order was not as it should be – the thing was attempting to boot from a drive with no boot sector! Duh!
Simple solution – get the drives into the right order again, and there you go, everything is hunky dory again. Must remember that, though it must be pretty unusual, as Goggling for the fault found no identical issues – had to use my noddle for once.