Help!!!!! Plx provide me an XP pro retail CD key!!!

My XP pro is partially dead because of my writing C++ code!

Now I can boot XP up and login, but I do not see the Desktop! That means there is no start bar, no Windows Explorer, no many other shortcuts!

However, I can still run the Windows Task Manager, where I can run IE, but not Windows Explorer, nor File Manager (I wonder if Microsoft provides it).

And even worse, I cannot find me XP installation CD! I tried to upgrade with SP2, hoping that may fix the problem, but it requires valid "XP Pro Retail CD key"!!!

I cannot even switch the IME and type Chinese for asking help!!! 5555555

Which XDJM can help me and provide a valid activation key??????