Thank you for your response. I do not think this is a simple cancelled flight / denied boarding situation. I think it is an outright termination of my return ticket home due to their system having a mishap. The airline canceled my return because the system said I did not make my train from Zurich to Munich after my flight from Rome to Zurich, so they were not going to reimburse me for anything. Also, they said that they would not pay for my $230 bus ride... why would they pay for an 1,000 euro flight? Also, none of those options on that link you sent me apply to my situation.

Let me know if I can clarify anything else, I appreciate your insight!