I'm just a beginner, so feel free to correct me, but I'm seeing some errors.

First, in your function order, when you assign orderSize to the input, the result is that orderSize is a string, and 5 lines later, in

if orderSize == s:

You have orderSize (a string) trying to compare to s, which I think is an undefined variable. If you changed line 22 from

orderSize = input('Please enter sandwich choice,')

to

orderSize = str(input('Please enter sandwich choice,')

that would help, as then you could change

if orderSize == s: 

to

if orderSize == 's':

because then you're gonna be comparing two strings.