@Aladdin-Alsati hi, there.
Thanks so much for taking your time to assist me.
No, my cloud is not connected.
I'm following the steps in the link you provided. In the terminal window I wrote "resetpassword". When I click enter or return key I'm prompted with the window reset password but there are more fields besides enter a new password for this user. One of them says "select the volume disc containing the user account". Sadly, is not showing anything and it's not giving permission to make any change in other fields.
Can you please help me to how to backup before a proceed to recovery OS? For me this would help a lot.
Cordially