How do I rollback changes in Ruby on Rails?

I'm using Cloud9 and I'm fairly new at it and I wrote a "rails g Scaffold" statement and ran it but I forgot to make changes before that. Is there any way I can rollback any changes made today to a previous date? The last time I worked on this was 3 days ago and I want to revert all changes so that my site looks like what it did 3 days ago instead of me starting from scratch again.