In Parashat Ki Teiztei, Perek 22, Pasuk 21, the word "na’ara" is spelled without a "hei" at the end, as if to say "na’ar". Also, in Ki Tavo, Perek 26, Pasuk 12 (and in other places), the word "natata" is spelled with a "hei" at the end. Usually "natata" is without a "hei" and just "tav+kamats". Why is this so?

Shalom, Nice question! The truth is that in all languages, the way of spelling certain words sometimes changes over history and from place to place (like color- colour). Those two examples which you brought, appear in the Torah spelled only as you mentioned, natata with a heh, and naíara without a heh. When we look at the Tanach as a whole, there are more than 20 examples where natata is written with a heh at the end, and less than half that, where itís spelled without a heh (as itís spelled today), and naíara is spelt both ways. In terms of why, the Abravanel explains that naíara (young women) is spelt naíar (literally, young man) in the Torah, to teach us that young women should, for reasons of modesty, be careful to dress in a way that doesnít overstress their feminine body. In addition, much has been written recently about the hidden codes in the Torah, found through skipping a specific number of letters, which may explain other examples of spelling changes in different places. Let us thank Hashem that today, the Hebrew language has been revived as a living spoken (and spelled) language, thus raising such questions, as your own! With Love of Israel, Rav Ari Shvat