Grad school hasn't responded to me two months after the results are supposed to be out I applied to a few grad schools and my top choice school hasn't responded to me. They confirmed they received my application and all my documents. I even got in touch with a professor who said she would be happy to take me into her lab. On the website, it says we should receive their decisions by the end of March, and right now, it's almost the end of May. I've tried contacting the admissions coordinator, left him a vm and email, contacting the professor, and also the people I was in touch with regarding my documents. No answer from anyone. 

Did they forget my application? What do I do? I don't think I'll be accepted at this point and I'll go to my second choice school. Can I ask for my application fee back?
It seems like a long time beyond their own deadline, but things driven by committee in universities get delayed. It is possible, though unlikely, that your application has been lost. And, it is usually the case that you hear earlier about a rejection than you will about acceptance. 

It is also possible that some communication has gone astray somehow. 

Don't despair yet about acceptance, but you are due some sort of explanation. If you are close enough to visit you can do that and talk to the head of the department or an admissions officer. If you can't visit, but can make a phone call, do that. You will be hard to ignore. Call any of the people with whom you communicated, but the professor would probably be a good choice. 

If you have to resort to email, let them know that you have other decisions pending and need feedback. 

But if they truly have lost your application, you should be able to request your application fees. But that seems the least likely scenario to me. The most likely is just the slow turning of the academic wheels.