I want to reset my laptop but unfortunately I can't access it when I start it because I forgot everything when I registered. And I can't open a second account either. What has to be done now?
Do you have a windows boot cd / stick? If so then reinstallation
If you have access to a Windows installation medium, you can also reset your password.
Assuming it is a local account and not in a domain.
Here is a little guide:
https://4sysops.com/archives/reset-a-windows-10-password/
This is a bit of an exaggeration, Windows passwords are easy to change if they are local accounts.
https://www.google.com/...+vergessen
https://www.passwort-generator.com/passwort-vergessen/
https://www.passwort-generator.com/passwort-wiederherstellen/
Forgot password - what to do?