To prevent entering U 12.04 I set my log in password to none (blank) Since then I can not authenticate as administrator as all possible passwords I tried are rejected. Besides, I can not enter recovery mode as the shift key does not work when rebooting. Any other way to enter Recovery M.?
If you installed the system yourself, your user will be member of
Try (in a terminal):
and give your own password.
If none of that works, boot into Ubuntu using a rescue CD (or USB key)
From there execute:
to reset passwords. Since the rescue shell runs as superuser, this won't ask the old password and simply set a new one. You should be done. This whole principle also works in general for many unixoid systems, not just Ubuntu or Linux in general.
by default. If you change that into:
all members of the group