I have a Vaio laptop and the F3 buttons doesn't work F3 + Fn changes volmune and same with Ctrl + F3 + Fn there is no Fn lock button, How do I open the coordinates especially since I get lost all the time. Also, how do I use display markers on a map? I tried using maps and searching on the internet.
It's not F3+FN, it's FN+F3.
An alternative would be to change your controls.
Pause the game, to access the main menu. Then choose "Options", and then "Controls". From here, scroll down until you find the command for the "Debug Window", click on the icon (it should currently be set to F3, as the default), then choose another button, like P for example.
This way, you won't have to worry about key combinations.