If a mistake was made during the weeks when the 4 Parshiyos are read and that week's Parsha did not get read during Krias HaTorah and this was realized after the davening, another Sefer Torah should be taken from the Aron and the appropriate Parsha should be read with the correct Brocha before and after. Kaddish is then said and the special Haftarah is read without the Brochos. Since a Haftarah was already recited for the weekly Parsha, no Brochos are needed.