go to https://github.com/sass/node-sass
download .zip or clone repo add el folder node-sass in node-modules and en file package-lock.json add this.
"node-sass": {
"version": "4.7.2",
"resolved": "https://registry.npmjs.org/node-sass/-/node-sass-4.7.2.tgz",
"integrity": "sha512-CaV+wLqZ7//Jdom5aUFCpGNoECd7BbNhjuwdsX/LkXBrHl8eb1Wjw4HvWqcFvhr5KuNgAk8i/myf/MQ1YYeroA==",
"dev": true,
"requires": {
"async-foreach": "0.1.3",
"chalk": "1.1.3",
"cross-spawn": "3.0.1",
"gaze": "1.1.2",
"get-stdin": "4.0.1",
"glob": "7.1.2",
"in-publish": "2.0.0",
"lodash.assign": "4.2.0",
"lodash.clonedeep": "4.5.0",
"lodash.mergewith": "4.6.1",
"meow": "3.7.0",
"mkdirp": "0.5.1",
"nan": "2.8.0",
"node-gyp": "3.6.2",
"npmlog": "4.1.2",
"request": "2.79.0",
"sass-graph": "2.2.4",
"stdout-stream": "1.4.0",
"true-case-path": "1.0.2"
},
ok now
~$ npm install