Hi.
Since you want to fix it yourself, I'll assume you have technical knowledge.
If it has a flourescent display, then I'd look for missing filament voltages. Also check the high voltage (usually around 30 volts) to the display. There is often a zener between the two voltages that shorts.
If it has an LED segment display, then it is usually a common supply that has failed to all of the displays as they are very reliable themselves. See if you have a main supply to the segments or driver ICs.
Mark
April 2009