If you are using local user to sign in, you will need to answer the security questions if they have ever been set up, or use a password recovery USB if you have made one prior to this.
Or, if you have another admin user on this computer you can log into, then you can launch netplwiz and change your own user's password while signing in as the other admin user.
Otherwise, there's no other way around this. You will need to clean install Windows in that case.