What would be the script for this?

[Cranky Old Man]

I want to do it so the when you try to open a locked door it will display a message only when you have a certain item. For example, you try to open door. It says "it's locked" when you pick up a key and try to open the door again it would say "try using the key to open the door" instead. It would say "try using the key to open the door" only when you have the key. What script would you type for that? (I'm a newbie with scripting).

You describe exactly what happens when you try to open a door in the first hub. Have you checked out how Frictional Games did it?
You can't except us to write an entire script for you, though. At least write as much of the script as you can, and we'll fill in the gaps.