wmic is not recognized as an internal or external command

Use the System File Checker tool (SFC.exe) to determine which file is causing the issue, and then replace the file. To do this, follow these steps:
a) Open an elevated command prompt. To do this, click Start, click All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator. If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.

b) Type the following command, and then press ENTER:
sfc /scannow
The sfc /scannow command scans all protected system files and replaces incorrect versions with correct Microsoft versions.

Also check if  Windows Management Instrumenation service is not running or not.

a) Click on start and type ‘services.msc’ in the search field.
b) Look for the  Windows Management Instrumenation Service.
c) The status should be "Starated" and Startup Type should be "Automatic"