Are you using SystemRescueCD...
chntpw is not in fact a command, it is a program with commands. Can you invoke it with the "-h" option to see that it is there and working?
http://pwet.fr/man/linux/administration_systeme/chntpw
You will not see anything happen if you are not in the correct directory. The file address given in the screen shot as an example may not be correct. I saw it elsewhere as
Code:
cd /mnt/disk/Windows/System32/config
You might google or use a live-cd to find and check on what the file name is in your Windows. All the variants I have seen end with"/system32/config" or "/System32/config".