You should try writing PATH variable to .bashrc file.
It’s located under your home directory, open your with any text editor:

nano ~/.bashrc

In try to locate does you have line that begins with:

export PATH=

If you don’t have it it in file, feel free to add it.
In your case it should be like

export PATH=/usr/local/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/sbin:/bin:/usr/games:/usr/local/games

Save it and close editor.
You can log out and log in again or use command to refresh it:

source ~/.bashrc

Try getting PATH from terminal and see if it is correct.

If you still get problem, maybe you should try removing nodejs package and checking is there node package. Then install by any method you want. If you want better version control, check nvm solution