login password unknown

I was using cygwin on windows xp and used passwd command but didn't want to enter a password so I pressed ctrl+D twice and without my knowledge some password has been saved for it. And now I am not able to login in windows after booting. I had set no password for windows login at all before this.

Please let me know what password must have been saved as a substitute for those two Ctrl+D keys, or, may be a way to remove the password by some means.

 

<Removed reference to password workarounds>

 

Sorry. The rules prevent password help.