Enable GUI in Windows Server 2012 R2 Core

To enable GUI to Windows Server 2012 Core do as follows

01. Mount the Windows Server 2012 ISO File
02. Open Power shell



Mount-Diskimage

ImagePath[0]: path to iso file
ImagePath[1]: leave blank



(Note : exit form the Power Shell mode)
03. Create a folder to mount the installation files

mkdir c:\mnt

04. get the index

dism /Get-WimInfo /WimFile:ISO file path

dism /Get-WimInfo /WimFile:d:\sources\install.wim 




(Note: the core instillation version in my case it was 4)

06.Mount the iso file with the created working directory

 dism /mount-wim /wimfile:d:\sources\install.wim /index:4 /mountdir:c:\mnt /readonly

07. Go to power shell mode

powershell

08. Install GUI feature 

install-windowsfeature server-gui-mgmt-infra,server-gui-shell -restart -source c:\mnt\windows\winsxs




This will restart the server and after the restart it will have the GUI interface.