It’s the nightmare scenario. You spend ages setting up your multi boot system and then to your disgust you find the Microshite Windoze system you left unsupervised has not only updated itself without asking your permission, but cheerfully shat all over your boot partition while doing so. The first you know of this transgression and wanton violation of your hardware is the sickening sight of the words “Grub Rescue>” where a boot prompt ought to be.
So what happens now ? Well, if you find yourself in this unenviable position, there are a couple of ways back.