I had an addon and when I had one of the items, I kept dying. Even in creative. I tried everything, even removing the addon. Minecraft still isn't functioning right.

I added an addon, at first it worked just fine until the next day when I went back into the mine with my Iron Hammer that I crafted the day before, It teleported me to my treehouse and I kept dying. So I turned off Instant Respawn and Respawning manually wasn't doing anything. So I went back to the main menu and deleted the addon and tried again, I still kept dying. I copied the world, Still kept dying. I set it to creative, still kept dying. This has never happened before with addons. Please fix, I've tried everything and I don't want to loose this world.