How does a Muslim make up for missed prayers and fasts if he has forgotten their number and days?

There are three scenarios for missed prayers:

1. Missing prayer due to an excuse like sleep or forgetfulness: It is obligatory to make it up immediately and in order, for the Prophet, peace and blessings be upon him, said: "Whoever forgets a prayer or sleeps through it, its expiation is to pray it when he remembers it."

2. Missing prayer due to an excuse that removes consciousness, such as a coma: The prayer is waived, and there is no obligation to make it up, because such a person is considered like a madman, from whom the pen is lifted.

3. Intentionally missing prayer without an excuse:

Denying its obligation: Such a person is a disbeliever, and he must enter Islam, and he is not obligated to make up what he missed during his disbelief.

Out of negligence and laziness: Making it up is not valid according to the correct opinion, because prayer is appointed to a specific time, and his action is rejected. Rather, he must offer sincere repentance, regret what has passed, resolve not to return to it, and increase in good deeds.

As for making up fasts, if the fast was missed during the period when prayers were also missed, he is not obligated to make it up, because one who abandons prayer is a disbeliever, and he is not obligated to make up acts of worship while he was in disbelief if he embraced Islam.