//If you transfered Your Project from another machime or from github then just
//Install react-scripts again !!
//UP vote if it helped you !
npm i -g react-scripts 

npm install react-scripts --save

npm install react-scripts --save

To Solve 'react-scripts' is not recognized as an internal or external command
Error First of all, just check if your package.json has react-scripts available
or not. If package.json has react-scripts then you just need to npm install
and then Your error will be solved. Just run this command: npm install If
package.json Doesn't have react-scripts then Just install react-scripts with
this command: npm install react-scripts –save Now, your read-script error must
be solved.
npm install
npm start
or
npm install react-scripts -save
npm start 

"scripts": { "build-css": "node-sass src/ -o src/", "build-js": "react-scripts build", "build": "npm run build-css && npm run build-js", "start-css": "npm run build-css && npm run build-css -- --watch --recursive", "start-js": "react-scripts start", "start": "npm-run-all -p start-css start-js", "test": "react-scripts test --env=jsdom", "eject": "react-scripts eject"
},

//If you transfered Your Project from another machime or from github then just
//Install npm
example: npm i
//UP vote if it helped you 

react script