Has anyone else noticed that we haven't even gotten to step 1 of the troubleshooting because we still don't have the basic information we need.(1) Get the backlight (if there is a backlight) working properly.(2) Get the contrast set properly.(3) Connect the Arduino properly.etc.Don
Michael presented very good and detailed 3 pages of how to wire it up and get it working,including a sample sketch (as shown in reply #26) and even a really nice wiring diagram on page 365(attached) and some debugging information in the section.
]There is nothing in the original post that mentions anything specific about the LCD that he is using or the code that he is trying to run it with. I don't see any mention about whether he is or is not using a shield as the word 'shield' appears nowhere in the post.