My 4 year old MacBook Air came on this AM. The keys are backlit and the curser shows but the screen is black. What is the problem?

I have a MacBook Air that is approx. 4 yrs. old. I've never had a problem with it. I closed it last night without turning it off. The only App. running was Safari. I plugged it in to charge. This is the way I have almost always closed it at night. this morning I opened it and found that the screen would not come on. I do have a curser and the keys are backlit but the screen is totally black. Does any one have any suggestions?