Even i faced the same problem because of python path was not added in environment variable ,follow below steps :
Go to Anaconda prompt type : where python
say it is C:\ProgramFiles\Anaconda3\python.exe
Open "Advanced system setting" from main menu. In environment variable,edit path and add path : C:\ProgramFiles\Anaconda3
Now in command prompt you see by typing : python --version
& the error "python' is not recognized as an internal or external command on CMD" will also go off.