//If you are using the NVM to use diffrent node versions
//Try to unistall the version witch is giving you problems, and install again
//Imagin that you are using the version 6.9.5, you need to follow the next steps
1 - nvm uninstall 6.9.5
2 - nvm install 6.9.5
3 - nvm -v (to test if the problem were solved)
//If the problem isn't solved try the following steps
1 - Open a new console out of your editor
2 - nvm uninstall 6.9.5
3 - nvm use x.x.x (choose other version that you have installed) (to check the installed version use the command "nvm list")
4 - nvm -v (to check if that version is ok)
5 - nvm install 6.9.5
6 - nvm use 6.9.5
7 - nvm -v (to test if the problem were solved)
Tip: if none of the steps above have solved your problem, try to close all your consoles and IDE to restart everyting, than open again and try to use the npm (e.g., npm -v)

;C:\Program Files\nodejs\