The Gemara (Berachot 21a) learns from the verse (Devarim 32:3) “Ki Shem Adona-i Ekra Havu Godel Lelo-henu” that there is a commandment to recite a blessing before studying Torah. Although there are opinions which state that this blessing is rabbinic in nature, the Rambam and others maintain that there is a biblical commandment to recite a blessing before learning Torah. As such, the Shulhan Aruch (O.H. 47:1) states that one must be very mindful about reciting Birkot Hatorah and about not learning any Torah before they are recited. Furthermore, the Bet Yosef (§ 47) implies that Birkot Hatorah is a type of Birkat Hamitzvot; just as one recites a blessing before performing other Mitzvot such as shaking a Lulav or donning Tefilin, one recites a blessing before performing the Mitzvah of learning Torah. It should be noted that “Birkot” implies that there are more than one blessing included in this commandment and indeed there are three which are recited immediately after Birkot Hashahar: “Asher Kideshanu Bemizvotav Vetzivanu Al Divre Torah”, “Veha’arev Na”, and “Asher Bahar Banu”.
One practical implication of Birkot Hatorah being a Torah commandment is if one is in doubt as to whether one recited them or not. Normally, if there is doubt regarding a blessing, the principle of “Safek Berachot Lehakel” is invoked. In other words, since reciting Hashem’s Name in vain is considered a serious offense, it is preferable to not repeat a blessing in cases of doubt. For example, if one were unsure whether one recited “Asher Yatzar”” after using the restroom, it is preferable to not recite it (again) at all. However, since Birkot Hatorah is biblical in origin, the Mishna Berura (O.H. 47:1), quoting the Sha’agat Aryeh, states that if one was unsure if one recited them one would be required to repeat them. The HIDA (Mahzik Beracha) writes that some rabbis posit that Birkot Hatorah are rabbinically-ordained and therefore if there is doubt as to whether they were recited, one would take into account Safek Berachot Lehakel, and not recite them.
Another implication is whether or not Birkot Hatorah need to be repeated later on in the day if one resumes learning Torah after coming home from work or some other interruption. The Shulhan Aruch (ibid:10) rules that if one has in mind to return to one’s learning after working, bathing, etc., then then they need not be repeated. Practically speaking, however, Birkot Hatorah are not repeated even if one did not have the express intent of continuing one’s learning later on.
It should also be highlighted that it is not permissible to study Torah unless one has recited the requisite blessings. Therefore, if one is becoming more observant and does not yet recite the morning blessings but wishes to attend Torah classes, it is proper for such a person to be taught to recite Birkot Hatorah early on. If there are sensitive issues at play or if one does not want to impose too many Mitzvot at once on someone who is becoming more observant, Rabbi Shlomo Zalman Auerbach (Halichot Shlomo: Birkat Hatorah) says that one can be lenient and not require them to recite these blessings from the get-go.
Summary: If one is unsure whether one recited Birkot Hatorah or not, one should not recite them again. If possible once should have one’s obligation fulfilled by someone else who is reciting them and who has one in mind. One does not repeat Birkot Hatorah if one resumes one’s learning later on in the day. One should not learn Torah unless one recites Birkot Hatorah first.