Hi Mokshazna
Make sure you have connected a pot. to VEE pin of LCD. You may also GND this pin for the highest contrast. Another reason could be that your C51 is not working properly or the code has not been burned properly; maybe due to some connection mistakes or so. To check this thing, try burning a simple code which deals with a LED (blinking or something similar) and check this out on your hardware. Try some sort of debugging techniques for this problem, you will surely find the solution.
Good luck 