RELOADING, RESETTING or REFRESHING YOUR COMPUTER
In the old days it was recommended that you re-install the operating system for your computer once a year.
Nobody ever did that and, fortunately, those days are gone.
However, a good old reset, refresh or reload can cure a lot of evils more quickly than mucking around with the constituent parts.
PUTTING A FRESH OPERATING SYSTEM INSTALL ONTO YOUR COMPUTER
The operating system of your computer is the part that bridges the gap between a useless collection of bits and pieces and a device that you can interact with.
It is software that makes your computer go.
Windows, MacOS, Linux, ChromeOS and so on to name a few (the best known few).
It is the platform upon which all other apps and software live.
Operating systems have a lot of built in features, apps / programs and it can be confusing to identify what's built-in and what's been added on.
Windows 10 alone, before you add anything else, consists of about 300, 000 files.
So there's a lot that can go wrong.
From failing hard disks, problemmatic upgrades to viruses, any number issues can mean that it is pragmatic to just "start again" instead of trying to repair.
But this isn't something you should enter in to lightly.
There are ramifications AND you do need to be prepared before your start e.g. make sure all your important data is backed up...
...and that you have plenty of spare time to work on the machine.