Need some Help for some command problem

When I tried to run it…by using " $gulp".
This problem is showing.
How can i solve it??
need help…

$ gulp
internal/modules/cjs/loader.js:985
throw err;
^

Error: Cannot find module ‘undertaker’
Require stack:

  • D:\All my project practice\bs4projects\bs4starter\node_modules\gulp\index.js
  • C:\Users\Farzana\AppData\Roaming\npm\node_modules\gulp-cli\lib\versioned^4.0.0\index.js
  • C:\Users\Farzana\AppData\Roaming\npm\node_modules\gulp-cli\index.js
  • C:\Users\Farzana\AppData\Roaming\npm\node_modules\gulp-cli\bin\gulp.js
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:982:15)
    at Function.Module._load (internal/modules/cjs/loader.js:864:27)
    at Module.require (internal/modules/cjs/loader.js:1044:19)
    at require (internal/modules/cjs/helpers.js:77:18)
    at Object. (D:\All my project practice\bs4projects\bs4starter\node_modules\gulp\index.js:4:18)
    at Module._compile (internal/modules/cjs/loader.js:1158:30)
    at Object.Module._extensions…js (internal/modules/cjs/loader.js:1178:10)
    at Module.load (internal/modules/cjs/loader.js:1002:32)
    at Function.Module._load (internal/modules/cjs/loader.js:901:14)
    at Module.require (internal/modules/cjs/loader.js:1044:19) {
    code: ‘MODULE_NOT_FOUND’,
    requireStack: [
    ‘D:\All my project practice\bs4projects\bs4starter\node_modules\gulp\index.js’,
    ‘C:\Users\Farzana\AppData\Roaming\npm\node_modules\gulp-cli\lib\versioned\^4.0.0\index.js’,
    ‘C:\Users\Farzana\AppData\Roaming\npm\node_modules\gulp-cli\index.js’,
    ‘C:\Users\Farzana\AppData\Roaming\npm\node_modules\gulp-cli\bin\gulp.js’
    ]
    }