I'm sorry to hear that :(
How long has the tank been set up, and did you have a filter?
Any ammonia reading over 0 ppm is bad, same goes for Nitrite. Fish produce ammonia as waste, bacteria converts that to NitrIte, and a different bacteria converts that to NitrAte. One has an I the other an A. Nothing but water changes or plants can get ride of Nitrate, but it is also the least toxic of the three. up to 20 ppm is okay with that, possibly up to 40 ppm but less is of course better.
Getting the bacteria is called a 'cycle' and it takes between 2 and 8 weeks, 4 on average, to complete.
Without live plants, 50% of the water should be changed weekly.
I'm afraid shrimp will do absolutely nothing in terms of this problem, shrimp produce waste too. They will eat left over food particles, which decay into ammonia, but they do not purify water.
Here is an article about the cycle that you may find interesting.