Forget admin local account password of windows server 2008r2

[Lucifer]

Forget admin local account password of windows .
We are using 2008r2 machine , i forget the password. Tried with installation disc , but in cmd when i am entering command cd c:\windows\system32 . It is saying path not found . Please suggest
I really need to rename utilman.exe file.

 

[Trouble]

It is saying path not found .

Typically, when you boot from external media your physical drives are not enumerated with the same drive letters as when booting normally, so
Do a
cd D:
then do a
dir
do that with sequential drive letters until the dir command shows you your Windows directory