when i go to saugus ironwork my overall game display become dark brown colour and it stays forever...anyone know what happened and how to fix this?

Get a new GPU?

I think you're looking for http://www.gamesas.com/forum/316-fallout-4-hardware-software-issues/

Whats a gpu ?

Graphic processing unit, a video card such as Nvidia Geforce as example.

If i load a earlier save game ,,the colour will become normal again..but thsts too far away back...

Did you choose the Scrapper perk with 2 stars? After you unlock this perk then everything that you have marked in your pipboy with a little magnifying glass becomes green in both the loading screen and in gameplay. You need to remove all the items you have as 'Tag for search' in your pipboy to get the game back to normal.

try this in the console : rimod 002041B6

it removes the recon scope effect which sometimes remains permanent

! remember to save before trying this command