Locked out of machine - please help

[Richard Kimber]

On Thu, 29 Sep 2011 23:18:43 +0100
Avi Greenbury <lists at avi.co> wrote:

> In the rescue session, can you add a new user? If you do this, does
> that user's username and password then work?

Yes.  I tried that and, after re-booting, was able to login using the
normal KDE screen using the new username and password.

However, I was unable to su to my normal user account - I get an
'authentication failure' error.

> Can you see what's in the password field for that (first) user and
> root in /etc/shadow? Do they contain only valid characters?

Well, it looks OK. The user entry has a very long string of characters
(92) where other entries are '*' but I guess that's normal. It's the
same for the new account I set up, and that worked OK.

> Is there anything in /var/log/auth.log to suggest precisely what the
> problem is, or indeed does the error on the console give any
> information?

Just 'authentication failure' errors where I have tried to login.

What would happen if, in recovery mode, I deleted all the users, and
then re-added my original user? (Presumably I couldn't delete the
root user, though - or is 'root' in recovery mode a different entity
from a normal root user?.) Would the files in the /home/user be affected
and would they keep the same UID and GID values? I'm getting into deep
(for me) waters here.

- Richard