Well, first place you gotta look is gore-editting mods that you have enabled, which might be just about any mod that has custom NPCs I suppose. Again I'd recommend trying the mods one by one to see if any of them cause trouble. I'd also recommend using a new world and character for this, since the absence of mods might mess up your current player and world, if there are mod items in them (which I guess they are).
You can just copy all the tModLoader files into your Terraria installation folder instead. I guess it's not working because of your absent or outdated Java installation