cmd.exe broken D:

So I go afk for a week..come back, and now when I try to do anything with the command prompt on winxp I get something like

'PING' is not recognized as an internal or external command,operable program or batch file.

I have absolutely no commands now in either cmd.exe or command.com and I have no idea how to fix it. Apparently the commands arent "in" the executable though, because I downloaded my friend's .exe and the same shit happened :/
Any ideas?

they're in your system folders. You can download ping.exe and put it in your working folder (DocSet/%CURUSER%/) and it should read it from there automatically.

they might have been removed by a virus. I can't imagine what else would do that except a slimming-XP type program that decreases the HDD usage of XP.

Don't forget to check that the paths are assigned properly. If you're using XP, check if the following works:
c:
cd \windows\system32
ping

sounds like the paths are fucked to me.