You say "However, when the user puts in the correct numbers, the second time," Have you tried putting in the correct number the first time? Does that work? I suspect not.
In all the world, there is not a number that is not either (that what the 'or' means) larger than 99999999999 or smaller than 9999999999990, so the else will never be invoked.
You want your if to read "if isbn is between 1000000000000 and 9999999999999". Check those numbers more carefully than the ones in the image to insure that one is the smallest possible 13 - digit number, and the other is the largest.