Connecting MacbookPro retina mid 2012 to 4k display

I tried to connect MacbookPro Retina 2012 mid 2.7GHZ 15 inches to 4k display using HDMI. It was working fine for few hours in 3840x2160 at 30 hz unfortunately when i changed the setting in display option to 1080p. I lost the above resolution option anymore. But when I login to my windows partition. It loads to the 4K resolution. I would love to have some suggestion, how to get back the 3840x2160 scaled out option in my Yosemite.

2) I would like to know if anyone have tried connecting 2012 mid MacbookPro with HDMI or any other connector with 60 hz. 30 hz is painfully lagging. Any suggestion would really helpful!