It seems unlikely that just adding a repository would have removed you from sudoers
(or more likely, the admin
group).
Are you still in the admin group?
Simply run 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 nano /etc/group
Look for the admin group and add your username to the end, like so:
admin:x:115:oli
You should then be able to reboot and be in the right group.
Has something melted /etc/sudoers
?
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!