Try disabling some of your mods, maybe one of them isnt working properly and is causing the game to crash, then you should go to the page where you downloaded that mod (or mods, as it could be more than one) and check if you meet all the requirements, keep in mind that the mod you are trying to get could not be suited for skyrim SE, as a lot of the classic skyrim mods are yet to be ported to SE. If your game doesnt run even after disabling all your mods, you might want to reinstall all the game files.
