I had fallout 4 installed and i was playing it on steam. Then i did some modding to my computer in which i pulled out the hard drives (They are back in now). Now when i go to steam it only gives me the option to install fallout 4 and not to play it. Is there some way i can update the directory in steam? So that i can show it where the game directory is or is it a different problem? I tried adding a game and going to the directory where fallout4.exe is installed but i get the same result.

did one of your logical drives get a different drive letter?

It looks like the drive where fallout is installed changed somehow.

you can check it in disk management. you can also assign a different drive letters there.

( my windows is in dutch, so i hope i translated it correct)

Yeah, it kinda sounds to me like the drive letters changed. Assuming Steam and it's library are not on your C: drive. If so, simply change the drive letters back to what they were before.

You are using a Steam library? You can see where Steam thinks the game should be. Open Steam and click the Steam in the top horizontal menu.

CLick settings and select downloads. Then click Steam library folders and that should tell you where Steam thinks the game should be.