If you used the scene viewer mod and saved, there is nothing anyone can do to fix the bugs it causes. You can fix the current bug (which is not a bug but the mod) but will surely keep getting similar bugs later on. That mod has a global script that will damage any save if you saved and caused all kind of erratic bugs in the game at anytime. You will have to start a new game. If you didnt save while using that mod, then I would suggest you used a clean copy of the game without the mod and see the problem happens. If not, then your in luck
I would still check your save but if this is the case and you saved using that mod, I nor anyone can help unfortunately. Sorry bro