Make sure you are typing in the procedure as it appears, i.e., it is case sensitive. For me, If I ever have any doubt as to wether I am typing it correctly, I go to explorer and just copy the file name from there.
Also, if the procedure requires parameters, it will not run without them.
If you restarted Maya, you should not need to source the script.
To do so though, you go into the script editor, Click on
file>source script, then find the file you want to source and click "Open".
When I am working on a programming project, I have a button on my shelf, where I insert code to source ALL the files that are in the scripts director, then whenever I start a new file, I just add it to the list. then whenever I need to source a file, I just press that shelf button.
"The Sage as an Astronomer: If you still see the stars as something above you, you lack the eye of knowledge." Friedrich Nietzsche