Can I cast enlightened tutor with no remaining artifacts or enchantments left in my library? If so, do I then reveal nothing to my opponents (by stating I have no artifacts or enchantments left in my library) and then shuffle my library ?
Yes you can cast Enlightened Tutor even if you have no artifacts or enchantments in your library. When it resolves you will just fail to find and not reveal anything. And will just shuffle your library.
Note - you can in fact "fail to find" even if you do have an artifact or enchantment in your library. Whenever you are searching a hidden zone for a specific card or card type you can choose to fail to find if you want.
Can I cast enlightened tutor with no remaining artifacts or enchantments left in my library? If so, do I then reveal nothing to my opponents (by stating I have no artifacts or enchantments left in my library) and then shuffle my library ?
Note - you can in fact "fail to find" even if you do have an artifact or enchantment in your library. Whenever you are searching a hidden zone for a specific card or card type you can choose to fail to find if you want.
Hope that helps and explains things for you.