Reset password without entered previous password .....

                  STEPS:-

1) Just open command prompt via administrator.

2) Type command "net user" to view all account of your pc.

3) Type command "net user <username> *" i.e. enter username of which you want to     change the password.

4) After entering command, a message occur "Enter your new password" & "Re-enter    your new password". & then command successful message occur.

                              OR

if you want to change the password in only one step:-

  Type command "net user <username> <password you want to rest>