Samsung Galaxy S5 Display quit working. Phone seems to work.

If you turn it off and turn it back on, does the screen show anything? Light? Something? If not, it might be the display panel.

It could be caused by a number of things, though... Faulty/loose connector, faulty display driver or burnt-out panel.

To see if it's the display driver, you could connect an MHL cable to your TV via HDMI... if the image appears on the TV, the driver is working.
 
I'll try the cable thing tomorrow. Other than that, there is nothing on the screen.

I'll post result tomorrow. Thanks