I really hope they reschedule rather than not letting you graduate because it's not your fault what's so ever. I was say talk to whoever you can about it but don't give up and fight it if you need to.

Sounds like an A+ to me.

Well, you’ll just have to wait until next year to graduate. Since you’ve finished up all of your requirements, you’ll have a solid year of partying ahead of you!

Immediately contact the dean (department head) and explain what happened.

Well hopefully you went on the right day if you did then I would talk with an administrator or some one so they know that you tried to do your interview. Hopefully they reschedule or you get the skip the interview

oh for God's sake. reschedule. shit happens. stop being do dramatic and reschedule.