local variable 'l' referenced before assignment...

[sparkz_alot]

Actually, you will get the same error, no matter which letter you enter. The letters (a-z) are defined in prealphabet and are local to that function, which means alphabet is unawares of their existence.  You could  include the contents of prealphabet to the beginning of the alphabet function and that would solve that particular problem.

You might want to start with a smaller version of your script, say 4 or 5 letters, until you get the bugs worked out, then expand it to include all letters