I did some wrong stuff with installation . Earlier i installed ruby 1.9.0, rubygems ( rails ) and rvm from source code . There was some unknown problem so ... i removed everything which has ruby word on it by this command

apt-get purge ruby*
Now ,
the problem is when i run this command
whatis ruby
whereis ruby
i get proper and acceptable response but when i try to run it with
rails new myapp
this thing will appear ..
bash: /usr/local/bin/rails: /usr/local/bin/ruby: bad interpreter: No such file or directory
i want to install Ruby on rails . Is there any solution other then formating and re-installation from stract
please help in , i wasted my whole day for this .. and you're my last hope.