Issue: End-user machine loses trust to domain and/or you forgot your administrator or account password. This is the easiest and fastest without a Windows reboot password CD.
Resolution: Need | Windows 7 boot CD, boot into repair mode and use command prompt. Copy c:\windows\system32\sethc.exe to c:\ (as a backup), then copy c:\windows\system32\cmd.exe over sethc.exe, overwrite, yes.
Reboot the machine into Windows once more, hit the shift key a few times and a command prompt will surface. Type net user username password (where username is the account and password is the password you are assigning). Note: If the account is a disabled account, then you will need to run: net user username /active:yes
Login with the new username and password