After installing Windows 2012 instance on google cloud, it drops to command prompt when ever I connect to it from RDP. It seems Explorer is not running on it. Any idea on how to fix this?
Sounds like it's running the Server Core version which doesn't have the GUI. You can type
sconfig to get a menu to configure the most common stuff.
I haven't used Google Cloud but on a regular Windows install if you are running the server core you can run
Add-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra from powershell to install the GUI.