Bash: ionic: command not found error while starting project in ionic 3

bash: ionic: command not found

while I start a new project this error is showing.

This the version is using on my pc windows 7.

Microsoft Windows [Version 6.1.7601]
Copyright © 2009 Microsoft Corporation. All rights reserved.

C:\Users\Dell>node --v
node: bad option: --v

C:\Users\Dell>node --version
v8.9.4

C:\Users\Dell>npm --version
5.6.0

C:\Users\Dell>git --version
git version 2.15.1.windows.2

C:\Users\Dell>cordova --version
7.1.0

C:\Users\Dell>ionic --version
module.js:540
** throw err;**
^

Error: Cannot find module 'C:\Users\Dell\AppData\Roaming\npm\node_modules\ionic*
bin\ionic’
** at Function.Module._resolveFilename (module.js:538:15)
*
** at Function.Module._load (module.js:468:25)**
** at Function.Module.runMain (module.js:684:10)**
** at startup (bootstrap_node.js:187:16)**
** at bootstrap_node.js:608:3**

C:\Users\Dell>