Hi and welcome.
Please edit your post above and put your code in [code] [/code] tags.
Easiest way to do that is to highlight your code and then click the # button above the edit field.
Read this post (click !) so you can prevent annoying people you like to get help from.
You said you have tried the 'Hello World' sketch, did you check everything is the same ?
I mean did you check this line ?
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
If the line in "Hello World' is different from the one you used in this other sketch, and 'Hello World' works, then you need to change the line in your own sketch accordingly.