My code doesn't work.

[wavic]

You compare two variables - 'choice' and 'a' - if choice == a:.

'a' is a varable with value "Nuclear Launch Codes". You are expecting user input to be the whole string "Nuclear Launch Codes"?

With if choice.lower() != "a" and choice.lower() != "b" and choice.lower() != "c" and choice.lower() != "d": you check if the user input is not a, b, c or d and if it is True why you check against a,b,c,d into the same code block? And you can do it better.

if choice.lower() in 'abcd':
    print("Your choice is", choice)
    if choice.lower == 'a':
        #etc.
    if choice.lower == 'b':
        #etc.