How Do I Change a Forgotten User Password Without Booting?

I can't log in to my root user's account. I've looked for a solution, but all of them tell you to do it from the boot options.

The thing is that my laptop's screen has turned black and it doesn't work anymore, so I've connected another monitor to the laptop so I can work on my computer, but I won't be able to see the boot menu on my new monitor.

Is it possible to change my password without using the boot menu?

Thank you!