Why am I suddenly not a sudoer anymore?

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http://askubuntu.com – I booted up Ubuntu 12.10 today, and when trying to sudo, I entered my password as usual but it had said I'm not a sudoer. So I go and check my account under User Accounts, and for some reason Im now a standard user? I tried re-adding myself to admin through recovery mode already, but it didn't work. EDIT: UserMod command will not work. Get the error: usermod: cannot lock /etc/passwd; try again later. (HowTos)