One of most important part of SharePoint setup is understanding the role of PSConfig.exe.
It is located at %COMMONPROGRAMFILES%\Microsoft Shared\web server extensions\14\bin
PSConfig.exe is an alternative interface to perform several operations that control how SharePoint 2010 Products are configured.
This is useful when you want to make changes related to Central Admin site like:
- Changing authentication
- Re provisioning of central admin site from one server to another
- You deleted site from IIS accidentally or screwed up in some other way
as a simple solution open the command prompt and navigate to path above and give following command.
> psconfig.exe -cmd adminvs -provision -port 42706 -WindowsAuthProvider OnlyUseNTLM
And its done. you will see new central admin site with port 42706 with default ntlm authentication.
You can find more details at : http://technet.microsoft.com/en-us/library/cc263093.aspx
Alternate to use PSConfig is obvious PowerShell.
“adminvs -provision” is now replaced with “New-SPCentralAdministration” in PowerShell.
So new command will be
New-SPCentralAdministration -Port 42706 -WindowsAuthProvider “NTLM”
Happy SharePointing 
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