Help please, why doesn't it show the next input?

[William Bryant]

Hey, I am very new to python, I am 13 years old. I want to be able to make a program the caculates the mean, meadian and mode. When i run the program, an input field pops up and says 'Does your list contain, a number or a string?' like I want it to, but when I type in something that is not one of valid field options: "String" or "string" or "STRING" or "s" or "S" or "str" or "Number" or "number" or "NUMBER" or "N" or "N" or "int" or "num", nothing happens, please tell me what I did wrong. Thanks :D Here is my code:

#-----           Variables that I am using, including the list.          -----#

#False means num
#True means string
num_or_string = ""
amount_numbers = []
List = []
I = "Does your list contain, a number or a string?"

#-----                      Functions that I am using.                    -----#
input(I)

def NOS():
    if I == "String" or "string" or "STRING" or "s" or "S" or "str":
        pass
    elif I == "Number" or "number" or "NUMBER" or "N" or "N" or "int" or "num":
        pass
    else:
        global I
        I = "You did not enter a valid field, :P Sorry."
        input(I)