If you pressed the INFO button, it can cause the screen to go black while taking photos. You can try pressing the INFO button to see if that brings back the screen. It's also worth pressing the MENU button to see if you're able to bring up the menu on the screen or not.
Otherwise, try shinning a bright flashlight at an angle to the LCD screen to see if you're able to make out a dim image. If you can, the issue lies with the screen's backlight.
It could also potentially be worth removing the back cover and checking to make sure that the screen's ribbon cable hasn't come loose at all.