I NEED HELP!!

My cat's name is Uriel and she showed up at my house 3 years ago. She is still an outside cat but we let her in for a few hours everyday.
A couple of days ago she killed a bird and didn't come home for 2 days. This had me really worried because she never not came home. When she showed up I noticed that she was not herself at all!
She will not eat food but will drink a little water. She will hardly walk either she only lays down and her breathing seems heavy.
Does anyone know what could be wrong with my baby???

When something like this happened with my cat, it was because he had a severe upper respiratory infection. He wasn't out as long as yours - he was fine in the morning, went out before I went to work, and when I came home, he was hiding under a car in front of my house. When he got into the house, he laid gasping for breath on my chest and sneezed blood on me. I was gone for maybe 9 hours, is all - this can happen very fast.

Take your cat to the vet. If there is an emergency vet, go there. What you're describing sounds like an emergency. My cat was okay in a few days, but he needed antibiotics and fluids in him quickly, and several days on a heating pad after that, in order to get to okay a few days later. If we hadn't gone right away, I might be telling you a much sadder story right now.

I desperately want to know what's wrong with her and im trying to get some money up a quickly as possible to take her.

We can't diagnose her over the internet - it sounds like a severe URI to me; another person might tell you it sounds like a broken rib or punctured lung. Someone else might think it sounds like something I haven't even thought of. All of us are going to tell you that she has to go to the vet. If you seriously don't have the money, call your friends or family and ask for a loan. She needs to see a vet and she came home to you like this because she trusts you to take care of her.