Would appreciate some help please. Game was working fine. A couple weeks ago I loaded the game, it loads fine but when I come to the game menu I press either a saved game or even try to start a new one, the progamme acts as if it is loading but then crashes completely and returns to the desktop screen without leaving any error messages?

If it's crashing when you start a new game it's likely to be related to mods. Maybe try a clean insatall.