It turns out that resetting your Windows account password is frighteningly easy as long as you have physical access to the machine.
The registry is just a database, and needed for the complex issues it solves. It’s true that things can go wrong.
Registry cleaners are widely available. When do you need one? Why? What’s the best registry cleaner if you do? In general, a registry cleaner isn’t needed and when it is, shouldn’t be used frequently.