Minecraft – My laptop doesn’t let me open coordinates in Minecraft

minecraft-java-edition

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.