rails server won't start - broke down the setup

rails server won't start - broke down the setup

Yesterday the app was running fine on development. Today, It asked about a
missing gem. I ended up upgrading the gems via sudo bundle install. At the
end, it didn't work either so I went back to gem 1.4.2. I'm using ruby
2.0.0p247, rails 4.0 and ubuntu.
When I type rails s I get:
boot.rb:6:in `require': cannot load such file -- bundler/setup
(LoadError)
I just can't figure out what went wrong. Bundle install says everything is
ready.