Reset password of gui user

Yes i can but i have a lot of errors because i am in the middle of some changes in my domain and dns.
EDIT: some error are not real! I read this post so i decided to check the ports using this website and they are open!

But for the sake of this post:

Is there a particular error that i should look for that could make me unable to change the gui user pass or reset it having access through console as root ?

tell me if you want me to paste results of the diagnosis anyway, I just wanted to avoid flooding.

Thank You !