Cannot run commands from command prompt?

Playing around with GRASS and Python, accidentally I lost environment variable resulting that some commands, like ipconfig and ping, from command promt were not running and the error was called.

Windows system32 directory should be left as one of the PATH variables.

PATH=D:\GRASS-64\etc;D:\GRASS-64\etc\python;D:\GRASS-64\lib;D:\GRASS-64\bin;D:\GRASS-64\extralib;D:\GRASS-64\msys\bin;D:\Python27;D:\Windows\System32