It sounds like you have an error. It’s really helpful to provide us some basic information.
What operating system are you on? Windows or OS-X? What version of the OS?
How old is your computer?
What version of Corona SDK are you using?
There should be a terminal or command window that provides you text output from the simulator to alert you to errors, warning, and your print statements. A really helpful tutorial to make sure you’re getting this information is:
http://coronalabs.com/blog/2013/07/09/tutorial-basic-debugging/
There are two main causes of a black screen: 1. you have an error in your code. 2. You’re running on a device that doesn’t support OpenGL 2.1. The 2nd problem can sometimes be solved by making sure you have the latest graphics drivers. Some computers are just too old and the video card makers may not be supporting old operating systems like Windows XP any longer. But without the basic info above, we can’t do much more than guess.
Rob