After renaming the computer without changing the worgroup or domain. whe the computer reboot I cannot logon to the LOCAL nor the Workgroups in the DropDown. What may caused this error. The error message at logon is : The system cannot log you onto the domain because the system's computer account in its primary domain is missing or the password is incorrect Please HELP?

Using the Local Administrator account login and password, login locally. From there you can remove the machine from the Domain login, add it to a Workgroup and then reboot the machine. You will then have to go to the DC and add the new Computer Account to the Domain, or if you have privileges, you can rejoin the Domain from the Workstation after logging in locally again, and then authenticating to the Domain using the account with the proper privileges.