IF Your display is a HD44780 compatible, but has no datasheet available: You can try tracing the connector pinout by using HD44780 datasheet as a reference.

All pins of the connector expect V₀ 1), possible V_ee 2) and possible Backlight power pins 3) are directly connected to the HD44780 controller.

If You have the basic electronics knowledge:

You should be able to trace LCD pinout by watching the controller pin arrangement and using conductivity tester of your Multimeter to trace signals to the connector pins. (the unknown pins are left to Your logical thinking ^tm to figure out)