'ping' is not recognized as an internal or external command operable program or batch file error

Most likely something has removed the system32 directory from your path. Have you installed the Java SDK? It has a reputation for doing that.

To check this, at the command prompt type path (followed by enter)

If c:\windows\system32 isn't there, it needs to be added back in. To do this:

From the desktop, Right click 'Computer', click 'Properties'
     then click 'Advanced system settings' 
            - this should bring up the System Properties - Advanced tab
Click 'Enviornment Variables'
Select the system variables 'PATH'
Edit PATH and add this line to the front
        c:\windows\system32;
or to be generic (in case you've installed windows on a different drive)
        %SystemRoot%\system32
Start a new command window to check if this has worked (or reboot)
      existing command windows will use the old path

Assuming you are using Win 64bit version of windows. Go under C:\Windows\SysWOW64 and see if you can find PING.EXE under the folder. If not, go download one. Someone or something(virus) might have deleted it

Edited: Go under C:\Windows\System32 to find PING.EXE if you are using 32 bit.