Cannot validate the php file. The php program was not found

Step 1: go to File->Preferences->User settings, A window will come up like the below image.


Step2: change the setting.json file like below image and save


If php is installed in your system simply set the path of your php.exe file like below:

"php.validate.executablePath": "C://path.to.your.php.folder//php.exe"