Redmine

Newbie here [it will be obvious as you go through this story too]
My installation that I am dealing with:

- Ruby implementation and version: ruby 1.8.7 (2010-08-16 patchlevel 302) [x86_64-linux]
- Rails version                  : Rails 3.2.19
- Operating system               : Debian GNU/Linux 6.0.6 (squeeze)
- Database used, and its version : MySQL Server version: 5.1.56
- Ruby-aware server used         : Don't understand, so I'm guessing Webrick

Background
All was going well as per the installation steps.
I got to Step 4. I did not know if my host had rmagick installed so I first went ahead with a Regular Install using

bundle install --without development test

After this I got the following error message

Can't install RMagick 0.0.0. Can't find MagickWand.h.
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/ruby1.8
Gem files will remain installed in /home/<user>/.gems/gems/rmagick-2.13.3 for ins                                                                                       pection.
Results logged to /home/<user>/.gems/gems/rmagick-2.13.3/ext/RMagick/gem_make.out
An error occurred while installing rmagick (2.13.3), and Bundler cannot
continue.
Make sure that `gem install rmagick -v '2.13.3'` succeeds before bundling.

I then tried to run an install without rmagick

bundle install --without development test rmagick

But that didn't work either.

So being the newbie that I am, I thought that if I delete all the files inside the

/home/<user>/.gems/gems
/home/<user>/.gems/bin

folders and re-run the installer without rmagick, it would all be okay.

It was not okay.

The installer didn't do much as I didn't see the gems folder get populated with anything.
So instead I got the list of gems and created a bash file to install all of them manually.

After which I executed Step 5 which went okay.
While executing Step 6, I ran into this error.

$ RAILS_ENV=production rake db:migrate
rake aborted!
no such file to load -- awesome_nested_set/version
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:251:in `require'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:251:in `require'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:236:in `load_dependency'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:251:in `require'
/home/<user>/domain.com/redmine-2.5.2/config/initializers/10-patches.rb:230
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:245:in `load'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:245:in `load'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:236:in `load_dependency'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:245:in `load'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/engine.rb:593
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/engine.rb:592:in `each'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/engine.rb:592
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/initializable.rb:30:in `instance_exec'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/initializable.rb:30:in `run'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/initializable.rb:55:in `run_initializers'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/initializable.rb:54:in `each'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/initializable.rb:54:in `run_initializers'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/application.rb:136:in `initialize!'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/railtie/configurable.rb:30:in `send'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/railtie/configurable.rb:30:in `method_missing'
/home/<user>/domain.com/redmine-2.5.2/config/environment.rb:14
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:251:in `require'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:251:in `require'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:236:in `load_dependency'
/home/<user>/.gems/gems/activesupport-3.2.19/lib/active_support/dependencies.rb:251:in `require'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/application.rb:103:in `require_environment!'
/home/<user>/.gems/gems/railties-3.2.19/lib/rails/application.rb:305:in `initialize_tasks'
Tasks: TOP => db:migrate => environment

Question
How can I undo the mistake I made in deleting all the files inside the /gems and /bin folder and go back to the start of the installation? I feel like I have dug myself into a big hole.