can we decode a string without knowing encoded format code example

Example: decoding encoding script for pythong

#novince coder, dont know if im doing this right XD
EncodingValues = ['q','w','e','r','t','y','u','i','o','p','a','s','d','f','g','h','j','k','l','z','x','c','v','b','n','m','Q','W','E','R','T','Y','U','I','O','P','A','S','D','F','G','H','J','K','L','Z','X','C','V','B',',','N','M','!','@','$','%','^','&','*','(',')','_','+','-','=','#']
encode = "this"

def encode(string):
  encodedcode = ""
  LetterToEncode = 0
  for i in string:
    LetterToEncode = LetterToEncode + 1
    encodedcode = encodedcode + EncodingValues.index(LetterToEncode)
    encodedcode = encodedcode + " "
    #still editing this
  
def decode(string):
  decodedcode = ""
  LetterToDecode = 0
  for i in string:
    LetterToDecode = LetterTodecode + 1
    if string.index(letterToDecode + 2) = " "
    decodedcode = decodedcode + EncodingValues.index(LetterToDecode)