I'd factory reset the laptop since it could have trojans or worse.
As to the password, it's no big deal. Read https://www.howtogeek.com/96805/how-to-reset-your-windows-password-without-an-install-cd/
and
https://www.google.com/search?q=windows+10+password+accessibility+reset&ie=utf-8&oe=utf-8
My stolen laptop was returned to me today. I did not set it up to be password protected and now someone else's login name shows up when I turn it on, with a box asking for a password.
How do I get rid of this so I can use my laptop again?
I don't know whether any of my personal stuff is still on the laptop - I doubt it, but I would like to check and be able to use my laptop.

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