SharePoint Central Admin not opening after Rename Sharepoint Central admin machine name

-Open Command Prompt (Run as Administrator)
-Run the following command:
Stsadm.exe -o renameserver -oldservername -newservername

Example :

C:\Program Files\Common Files\Microsoft Shared\web server extensions\14\BIN\Stsadm -o renameserver -oldservername Sharepointserver -newservername SpServer