All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Your friend should forget these wishes, perform deeds of the people of Paradise and save himself from Hellfire. This is better for him than wishing for things that are nothing but evidence of simple and narrow-mindedness.
If he enters Paradise and is saved from Hellfire, he would not worry about what he is, even if he is an animal. On the contrary, if he enters Hellfire, nothing can benefit him, even if he is the strongest man ever or the most beautiful woman ever. A Muslim should be concerned about how to please Allaah, enter Paradise and be saved from Hellfire. If he enters Paradise, he will get whatever he desires.
Changing one’s sex is something that does not really happen, and it is only Allaah Who can change people’s sexes. The transvestites, who consume drugs to change their sex, claim to be females but they are in reality males who had their breasts enlarged and had their penis cut –we seek refuge in Allaah from the deterioration of our Fitrah.
These people will be resurrected on the Day of Judgment as males exactly in the same form as Allaah Created them and Brought them out of the wombs of their mothers.
Allaah Says (what means): {As We began the first creation, We will repeat it.}[Quran 21:104]
Ibn Jareer said: “This verse means that Allaah will bring the creation again on the Day of Judgment bare-footed, naked and uncircumcised exactly in the same shape [and having the same features] as He created them at the first place in the wombs of their mothers.” For more benefit, please refer to Fatwa 85575.
Allaah Knows best.