how can I fix my 6-disc car stereo with model no. GL2T-18C815-BK?

my 6-disc car stereo is working but it does not display anything on the screen, i mean the timer is just blank but it is playing and i can hear the sound. the make of the car is ford and the car stereo is made in mexico. the model is gl2t-18c815-bk while the serial is gj9k005400 thank you.