How should I write an email asking about the status of my PhD application? I applied for a PhD position. As part of the admission process, the professor requested two letters of recommendation, which have been sent. I was then asked to wait a week, but now two weeks have passed and I have not heard from the professor yet. So, I would like to ask about the status of my PhD application. I have no clue how to write it. Please help!!! 

Thank you in advance.
I wouldn't make too much fuss about it. A simple short and polite email which states that the current state of affairs (letters were sent, you were asked to wait for a week) and inquires whether there were some problems with your application and what its status is.

On the side note, a week waiting is not at all alarming in academia, unless some explicit deadlines are in place. I would wait for at least another 10 days before contacting the professor.

I also agree with RoboKaren, it is highly unusual to apply to a professor. Therefore, another cultural/professional practices may apply in your case. However, a polite email is almost always acceptable (whether or not it is ignored is another question...).