If a person washed Netilat Yadayim to eat bread, and after drying his hands he realized that he had forgotten to recite the Beracha of "Al Netilat Yadayim," should he recite the Beracha at that point?
The Rama (Rabbi Moshe Isserles, Poland, 1525-1572), in his glosses to the Shulhan Aruch (Orah Hayim 158), writes that although one should certainly recite the Beracha before drying his hands, if he did not, he should recite the Beracha after drying his hands. This ruling is based upon the view taken by some Rishonim (Medieval Halachic scholars) that one who did not recite the required Beracha before performing a Misva may recite it after performing the Misva. According to this view, even though one did not recite the Beracha of "Al Netilat Yadayim" before completing the Misva, he may still recite the Beracha afterward.
However, the Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204) was of the opinion that one may not recite a Beracha over a Misva after the Misva is completed. According to this view, after one dries his hands, and has thus completed the Misva of Netilat Yadayim, he can no longer recite the Beracha. This is the view accepted by Sepharadim, and therefore one who did not recite the Beracha of "Al Netilat Yadayim" before drying his hands should not recite the Beracha.
If a person has a bandage on his hand, may he wash Netilat Yadayim, and, if so, does he recite a Beracha over the washing?
Generally, when a person wears a bandage over a cut or a bruise, the bandage covers not only the actual bruise, but also the area surrounding the bruise. Hacham Ovadia Yosef therefore rules that one should preferably remove the bandage before washing Netilat Yadayim, so that all the non-injured skin on his hand can be washed. If one cannot, for whatever reason, remove the bandage, then he may wash Netilat Yadayim, but in such a case he should not recite a Beracha, since part of his skin is blocked from the water.
If a person wears a cast, such that he cannot wash Netilat Yadayim at all on one of his hands, then he should wash Netilat Yadayim on his healthy hand, and recite a Beracha. This is the ruling of Hacham Ovadia Yosef, based upon the view of the Zibheh Sedek.
Summary: A person who washed Netilat Yadayim but forgot to recite the Beracha of "Al Netilat Yadayim" before drying his hands should not recite the Beracha. A person with a bandage on his hand should preferably remove the bandage before washing Netilat Yadayim. If he cannot, then he should wash Netilat Yadayim without a Beracha. A person with a cast on one of his hands may wash Netilat Yadayim on the other hand, with a Beracha.