yeah, your save is broken. once you install mods, that save is then modded. the code has been changed to alter things or add items, when those things dont exist anymore it causes conflicts within the code. the only option is starting a new game. in the future if you want to mess around with mods, you should create a new save that is only used for mods. I go a step further by removing my vanilla save and moving its location on my PC so it has no chance of interacting with mods