There’s a few things you can do to narrow it down for us. Firstly, like it sounds you have, be sure to check and try to load up some official and non official mods. That’s just so we know how many or all the mods it’s affecting. Secondly, try loading the mods in single player. If it doesn’t works definitely send some screenshots showing it. If that doesn’t work, the third option I’d say since you’ve tried reinstalling and I’m sure haven’t been touch and moving files around, is to use the mod maker. Open it up with ctrl+m to see if it force loads the objects and mods at first, if not you can try placing an object and testing to see if making a new mod will let you load.
I can’t imagine an issue past the mp side of it but in case it’s not, there’sstill a lot of back end info we need to make sure we have so we appreciate all the info you can help us out with.