Jews Jews Jews??????

You seem to be asking two different things. Mark and Cher have given you perfectly good answers to the question about the loss of Torah (for which I have seen no evidence whatsoever). You also ask about the issue of Ishmael's age. Actually, the problem of ages in the Tanakh doesn't apply only here. I don't have a relevant commentary to hand, but I seem to remember that there are various possibilities about how age is calculated, which may not be on the annual basis we see as the norm. You're right that if we take the ages given in the annual way we're used to, the story is a bit hard to follow. But to get hung up on such literalism really doesn't do the story any service. I'm sure you get the key issues.