authorization procedure locks up after administrator password changed to null

[Mike Lachowski]

i changed the administrator password to null string. after that I tried to change it to some real string i could not pass the unlocking procedure of the password change screen, the null string dont work and the previous password dont work as well.
however the installation is now unprotected, as i am able to log in into administrator user account without password.
I tried to revert to earlier version of ubuntu, but the bug spilled to there too.

If i knew how, i would delete and reinstall the ubuntu, saving my data firs, but as the ubuntu is installed parallel to windows, it is beyond my skills

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1037973/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Robert Ancell (robert-ancell)]

Closing assuming fixed.