My user lost root privilege after try to add the user to a group. It's looks like the "usermod xxxx --groups ..." change the from the root group to the new one, it's a mistake but the thing is my user lost all root privilege and as you know, ubuntu un the instalation process ask to create an user (the uniqueone I have) with root privilege but never ask (if I'm not wrong) to give an password to root user.
How can I fix this? how can I recover root capacity?
Yesterday I tried to boot in "save mode" but I couldn't, I have just ubuntu installed in my PC and when I tried to get the grub windows (whit ESC) it just show a console with "GRUB>" and some instructions that I`ve never seen before and don't understand.
I don't know what to ...