A few possibilities:
1.) Press the "INFO" button on the back of the camera. Upper Left, right next to the eye cup. Press it repeatedly and it should cycle through the different modes. One of the modes is actually "LCD OFF", so that could be the culprit. 2.) Also make sure that the rubber "eyecup" padding has not slid up 1/4 inch and covered the "display off sensor" that turns the display off when you put your face up to the camera. If that rubber eye pad (or dirt or makeup or your thumb or anything else) is covering the sensor, then the display would turn off thinking you have the camera up to your face.Any help at all?
If neither of those have any impact you might actually be looking at a hardware problem that has to be resolved by the shop. But really make sure that the sensor isn't blocked with dirt, makeup, or something else. It is a very common issue.
If you have done that, pulled the battery for 60 seconds, and nothing has an impact then the only recourse you really have is to take it in for repair.
I am sorry, I wish that I had better information for you. But this issue has happened many many times, and there aren't very many troubleshooting steps that can be gone through.