To allow one of my users ssh access I added the lineAllowUsers userto my sshd_config. I gave the box a reboot and attempted to ssh back in as superuser. I was unable to do so. I have my keys- both public and private locally, but I'm guessing the change in the config is preventing me logging in.  However I can get into the user account. This is just a EC2 VM, so there's no desktop trick I can try.user has just standard permissions
Changed /etc/ssh/sshd_config. Now can't get to SU. Am I screwed?
ssh;root;amazon ec2
To quote from the sshd_config manpage:AllowUsers              This  keyword  can  be followed by a list of user name patterns,              separated by spaces.  If specified, login is  allowed  only  for              user  names that match one of the patterns.With this setting, the only user you can log in as is the one you specificed on the AllowUsers line. If you can login as this user, and use either su or sudo to become root, you can regain control of the machine and fix the config file.If you are using EBS, you can shut this machine down, mount the EBS on a different machine, and fix the config file, and then recreate this VM.