laravel 5 : Error running php artisan php.exe

i want to run php artisan in terminal, i got error php program, and i try composer update and didn't work, how to fix this error ?

Program 'php.exe' failed to run: The process cannot access the file because it is being used by another processAt line:1 char:1
+ php artisan
+ ~~~~~~~~~~~.
At line:1 char:1
+ php artisan
+ ~~~~~~~~~~~
    + CategoryInfo          : ResourceUnavailable: (:) [], ApplicationFailedException
    + FullyQualifiedErrorId : NativeCommandFailed

via Chebli Mohamed