I would suggest (if possible) that, on the grounds of simplicity that you reinstall Ubuntu.
When you are asked to give a user name, do so and give it a reasonable password.
This user will have normal abilities for user purposes and should be used for your logon.
If you use the sudo command you will be able to perform root level admin functions with it.
Ubuntu doesn't have a password for the root user.
In the unlikely situation that you need to logon as root there are methods to give it a password.
But try to avoid the temptation to do this.
Don't use root.