Backup laptop was hacked

Suspect my old laptop was hacked (HP Envy). Why? my login password was refused and marked as incorrect when I try to login. Reboot the computer and found out the user name was the one that I never created.

Wait so the bootup credentials have been changed? Correct me if I am not clear about it.

Yes. The user account at the login screen is not the one I set previously.

Ask your family if they have done anything to your laptop, does your laptop only have one account ? you can get into your laptop with other accounts ,then remove the "Unknown account " on your laptop .

No, they didn’t touch my computer

Check if this is a guest account or the admin account, if this is the admin account, best suggestion is to reinstall the windows version installed on the laptop, this can removed everything that is saved in the laptop including the privilege of unknown user.

Ok , i see , but you can login your laptop with guest account or super account ,it is one way that works.
If you don’t have any other accounts on your laptop , all you can do is brute force cracked it .
You can do it like this :

If you Log into other accounts on computer,then unlock the locked account,that works,but i have never did that,and i have never seen anyone do that.
As for brute force crack the password,can you make sure that nothing else in the computer is damaged?
By the way,these two tutorials will let you how to reset password witout losing.