In case you haven't looked at the other threads that have been posted recently here is what you should do:
(0) You have used enough solder to connect two or three LCDs. Make sure there are no 'cold' joints and no 'solder bridges'.
(1) If the module has a backlight then get it working properly. This involves only pins 15 and 16 on your LCD module. Make sure to use a current limiting resistor if there is none on the LCD module.
(2) Get the power and contrast working properly. This involves only pins 1, 2, and 3 on your LCD module. You should be able to see blocks on one row of a two row display and on two rows of a four row display.
NOTE: The Arduino has not been used yet, except as a possible source for the power needed for the first two steps. Do not try to go any further until this is working. If you don't see the blocks then no amount of program code will help.
(3) Connect the LCD R/W pin (pin 5) to GND.
(4) Connect the six control and data wires between your LCD module and your Arduino.
(5) Upload your sketch and it should work.
If you still don't get a display then make sure that your wiring matches the numbers in the descriptor (or vice versa).
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);If you get a display but it is garbled or has some other problems then try again with a 'static' sketch, one that displays a simple message on the top row of the display and then stops. All of your code should be in setup() and loop() should be empty between the brackets.
LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // put your pin numbers here
If you are still having problems then we need to see a photograph of your setup that clearly and unambiguously shows all of the connections between your Arduino and your LCD module.