• If masturbation is accompanied by climax, then it breaks the fast and prayer is not valid unless you do Ghusl. If it is not accompanied by climax, then your prayer and fasting are valid. • If a person masturbates and is ignorant of the ruling that it is obligatory to do Ghusl afterwards and that it invalidates the fast, the majority of scholars are of the view that it is obligatory to make them up. Some scholars are of the view that it is not obligatory.

If you engaged in masturbation but no semen came out as a result, then the fast is not invalidated. If it did come out, then the fast was invalidated and you have to make up the missed day.