Please elaborate on "nothing shows up". Do you get a 404 error? A 500 error? A cPanel "Great Success !" page? An infinitely loading page? Just a completely blank page?
What's in the script? The extension is .php; is it supposed to execute some PHP, or is that just the extension? If it is actually PHP, please check in the ~/public_html/ folder for a file called php_error. If it exists, download it to your computer, open it, and see what it says; your script may just be dying and not outputting anything to the browser. Optionally, replace the entire contents of the file with a single line of text - something like "Hello world" is good. If that is output, then we know that the file is being opened, and the problem is just with the previous contents of the file.
--- Mr. DOS