It seems unlikely that just adding a repository would have removed you from
sudoers (or more likely, the
Are you still in the admin group?
groups from a terminal. You should see a list come out. You're looking for the word
admin. If that's in there, this isn't your issue.
The easiest way to restore your
sudo rights is to reboot in recovery mode (hold left-shift at boot, select a recovery mode kernel, boot to the root prompt). Once in there you might be able to run (swap
oli for your username) :
adduser oli admin
But I've seen some thing that suggest this might not work from a recovery console. Try it. If that doesn't work, or you want to check, run
Look for the admin group and add your username to the end, like so:
You should then be able to reboot and be in the right group.
Has something melted
Unfortunately you can't read
/etc/sudoers unless you're root. So back to recovery mode (as above). Once you're in there run
nano /etc/sudoers. You're looking for a pair of lines like this:
# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL
If that's there, this isn't your problem. If it's commented out or missing, whack it back in there!