What is the ruling on prayers performed without ghusl due to ignorance of its obligation, and how can an unknown number of these prayers be made up, and is it permissible to postpone making up these prayers?

Ghusl is not obligatory for masturbation unless semen is discharged. If you prayed while in a state of janabah (major ritual impurity), your prayer is invalid and must be made up, even if you were unaware of the obligation of ghusl. If you do not know the number of missed prayers, strive to estimate and make them up. As for combining making up missed prayers and performing sunnah prayers, you should strive to make up the missed prayers, and it is permissible to forgo the sunnah prayers. However, it is preferable not to abandon the Fajr and Witr sunnah prayers. If the missed prayers are numerous, it is better to confine yourself to performing the obligatory prayers only. Some scholars have made an exception for the Fajr and Witr sunnah prayers.