sudo and all admin accounts disabled?

[Jordan Miller]

we have the latest ubuntu installed. everything was working fine. all  
of a sudden, we have no superuser access. all admin accounts that  
were previously working fine now have no ability to run sudo or sudo - 
s with the error that these usernames are not in the sudoers file.  
However, I know they were all admin accounts when they were setup. I  
know this is not simply someone taking away my privileges because I  
setup all admin accounts and have checked each one and they are all  
not allowed to do a sudo or a sudo -s.

do i need to do a reinstall? Please advise.

thanks,
Jordan