Does masturbation after repentance bring a curse, and does it necessitate making up the fast if it occurs at night during Ramadan, and is it obligatory to make up prayers missed due to not performing ablution for two years?

Masturbation is forbidden, and if a person persists in it, it becomes a major sin. Repentance erases what came before it, and you are not required to offer expiation other than repentance. As for one who masturbates during the night of Ramadan, he is sinful but is not required to fast the day. However, whoever masturbates during the daytime in Ramadan and semen is discharged has committed an act that breaks the fast, according to the majority of scholars.

As for the prayers you performed without ablution or missed after puberty, there is a difference of opinion regarding the obligation to make them up. If you suffer from obsessive-compulsive disorder, there is no blame upon you for adopting the view of Sheikh al-Islam Ibn Taymiyyah, which states that making them up is not obligatory. Instead, you should increase in seeking forgiveness, sincere repentance, and performing supererogatory acts of worship. As for what occurred before puberty, you are not held accountable for it.