my npm just disappeared!!??

For the last few months, this has been happening to me and its really annoying. If I update npm without root privileges like this

$ npm update -g npm

while I know I should have done this

$ sudo npm update -g npm

updating npm fails with EACCES & the symlink from /usr/local/bin gets deleted.

If you run npm now

$ npm
-bash: npm: command not found

To fix this, just recreate the symlink

$ sudo ln -s /usr/local/lib/node_modules/npm/bin/npm-cli.js /usr/local/bin/npm

and npm is your friend again.