When you're inside your Orbiter simply press the "Esc" button and then select the bottom option to "Exit the Game". It is as simple as that.

damn the image won't load up I mean when you are bugged in the forge upgrade menu in railjack and you can't do ANYTHING to close it or even quit the game

That hasn't never happened to me before. Might be better to use a Steam screenshot of it and then post it upon the WarFrame's "Support" site[support.warframe.com] to get it solved because rather rarely, if anytime at all, their dev' team steps inside the Steam forums when they've got ther official ones? (Even if albeit those are still sort of police moderated, which is mostly why I still prefer to hang around these here parts.)

just now I have restarted a railjack mission after failing it, but after loading up the mission the entire hud was gone and I couldn't open up the menu to exit or do anything else than walk and interact with the ship.

And before this I played my first railjack mission in months but the hud was also not present except for the chat, but pressing esc worked to open the menu.