If somebody eats a Ke’zayit of Mezonot food (such as crackers or cake) and also drank a Rebi’it of wine, then he recites a Beracha Aharona including both the text of "Al Ha’mihya" and "Al Ha’gefen," to cover both the Mezonot food and the wine.
The work Yalkut Yosef (Berachot, p. 496) rules that if a person in this case recited only "Al Ha’mihya," forgetting to include the text of "Al Ha’gefen" for the wine, he must then recite another Beracha Aharona over the wine. (Of course, he recites only "Al Ha’gefen," without reciting "Al Ha’mihya.") This is also the position taken by Hacham David Yosef, in his work Halacha Berura.
However, the work Hazon Ovadia (Berachot, p. 189) notes that this was not the view of Hacham Ovadia Yosef. Hacham Ovadia discovered that according to some Poskim, one does not recite a second Beracha Aharona in this case, as the text of "Al Ha’mihya" is considered to have covered the wine, as well. Even if one did not have any intention for his Beracha to cover the wine he drunk, nevertheless, according to these Halachic authorities, he does not have to recite another Beracha. And since some Poskim adopt this position, one should not recite a second Beracha in such a case. This is the ruling codified in the English edition of Yalkut Yosef (Berachot, p. 220), which advises one in this situation to drink another Rebi’it of wine so he will then be required to recite another Beracha Aharona according to all opinions. But if one does not have access to more wine or does not wish to drink more, he does not recite another Beracha.
Summary: If one ate Mezonot food and drank wine, but in the Beracha Aharona he mentioned only "Al Ha’mihya" without "Al Ha’gefen," does not recite another Beracha, though preferably he should drink another Rebi’it of wine and recite "Al Ha’gefen."