what do you mean, may ilaw pa din yung clock but the display is blank? you mean, the digital clock's numbers are blank, but the two dots in the middle are glowing?
most strange...
try the setting buttons. baka na-stuck lang..
or, kapain mo yung sa likod niya.. baka may na_pindot o "na-ground" lang..

errr. what car are we talking about? in my sentra, the LCD clock is on the speedo dial..