I have graphic LCD JYG-12864B4C-VB . But the problem is that i don't have its datasheet. I searched the whole Google but didn't find. If anyone of you have used this GLCD, kindly share its datasheet.
I suspect the part number, JYG-12864B4C-VB, refers to the entire module, GLCD and buttons, rather than the actually GLCD itself. It appears to be a 128x64 GLCD, probably based on a common driver chipset like the KS0108/KS0107 or compatible, however you might need to breakout a multimeter and trace the connections from the actual GLCD to the pinouts at the base of the PCB. A search for KS0108/KS0107 compatible GLCDs is probably a good place to start. Also, if you can figure out which are the power, GND and some other the other pins of the actual GLCD and then compare your devices pinout with the pinouts of some of the more commonly manufactured 128x64 GLCDs, chances are you may find a datasheet which is compatible with your display.
You should be able to determine the power and GND pins by their relation to power traces and ground plane of the PCB.
As many of these devices operate in the 5V to 6V range, unless you inadvertently switch those connections, you should be able to safely try various data and signal connection arrangements.
I've attached a datasheet for a generic KS0108 compatible chipset 128x64 GLCD which may or may not match your device in pinout and function.
A quick search for 128x64 GLCDs would yield other alternative datasheets and chipsets of they are based.
BigDog