I had a problem with the installation of express. Problem was I had two version installed in two different directory. I tried to uninstall the two versions deleting files of node and the directory node_module. Then I installed one more time node, but now npm doesn't work:
/usr/bin/npm: /usr/bin/nodejs: bad interpreter: No such file or directory
What I have to do? I only thinked that best way is remove every files of nodejs and reinstall it, but I don't know how.
You installed node without removing the older version you had installed. You can follow the instructions given here to remove all nodejs fies :https://npmjs.org/doc/removing-npm.html
After doing the above also do hash -r to remove npm location from hashmap, before reinstalling it.