What is the ruling on obligating a sister afflicted with epilepsy and mental retardation to pray and fast, knowing that she was previously observant of her prayers, but now she refuses them and forgets some basic information?

The intellect is the basis of religious obligation (taklif). Anyone who is insane or mentally deficient (ma'tuh) has no valid legal dispositions according to Islamic law. It appears that the sister is in a state similar to that of a mentally deficient person, thus she is not religiously obligated and cannot be compelled to pray or fulfill other religious duties. Ibn Qudamah said: "The insane person is not obligated, and he is not required to make up what he missed during his insanity, unless he regains consciousness at the time of prayer." The Messenger of Allah (peace be upon him) said: "The pen has been lifted from three: from the sleeper until he awakens, from the child until he reaches maturity, and from the mentally deficient person until he regains his intellect." Treatment, ruqyah (spiritual healing), and supplication should be sought for her.