Server 2012 r2 only boots to command prompt

1. it's usual for server core 

2. try to run server manager (just type servermanager in cmd)

3. try to view installed GUI feature using powershell

                  type powershell

                  get-windowsfeature *GUI*

                  verify that you have Server-Gui-Mgmt-Infra and Server-Gui-Shell  installed

4. if 3 is false , install GUI features:

                   Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell -Restart