This has been my go to for years now. It’s especially useful whenever a friend or family member hits me up with a “computer question” that inevitably leads to “let’s just reinstall whatever you had before” and I just need something quick that works.
How do ordinary people manage bung up their systems so badly that the thing to do is reinstall the whole thing?
And this happens often enough that it’s worth carrying around a tool to do this? I thought that by now systems would be adequately armoured against this.
Within the last year on the same system I've had both windows 10 and a linux install commit suicide via update with no particularly special conditions. I later figured out what happened with the linux system only after some frustration and paving over it. It was a defect in a distro provided config file that resulted in the initramfs not having the proper support for the filesystem.
With windows no automated repair could fix it and the whole system is so opaque that I will probably never know what happened other than it works after reinstall.
Even if nothing ever goes wrong you will eventually need to install to a new system and usb drives are incredibly cheap with a 64GB USB 3.1 weighing in at all of $8-$12. You needn't carry it around just stick it in a desk drawer.
Usually there is a recovery partition, and Windows 10 has a built-in function for a refresh/reinstall from the recovery partition. No USB drive needed. I did this recently over the phone for a relative's computer, but I forgot the exact name of this feature in the settings/control panel.
In my case, it was necessary because the computer had not been used for months and was unable to connect to various websites, perhaps due to an out-of-date certificate. Rather than troubleshoot the issue, it was easier to just do the refresh.
"Reset this PC" is one possibility that you're thinking of. Has options for saving or deleting all user-dir files, (afaik) always removes installed applications. Can also fully format the disk, and pull a clean copy of the installer from the 'net.
I ran distro upgrade on Fedora and it destroyed my grub. This is unusual, I ran several distro upgrades without issues, but this time it was different.
I am no expert on grub and after spending 20 minutes trying out various solutions from the Internet I gave up and ran a quick reinstall. At least most of it was unattended and I had a clean system as a result.
