LCD Screen has has no light to it anymore

Question

The main LCD screen on the back of my Toshiba M700 camera has become almost unreadable. You can barely tell it is still working if you are in the light but in the dark you can't see anything on the screen. I would like to know what is wrong and how to fix it. Everything else seems to be working properly. The camera is about 3 years old.H E L P !!! if you can.Thanks,Ernie/