What is the expiation for not praying and fasting while in a state of ritual impurity (janabah) without a valid excuse, given repentance and ignorance of the number of missed prayers/fasts?

Missed prayers due to a legitimate excuse such as forgetfulness or sleep must be made up (Qada'). This is based on the Prophet's (PBUH) saying: "Whoever forgets a prayer, let him pray it when he remembers it, for Allah Almighty says: 'And establish prayer for My remembrance.'" As for prayers intentionally omitted, the majority of scholars are of the opinion that they must be made up, and this is the most preponderant view. This includes praying while in a state of major ritual impurity (janaba) or without ablution (wudu'). If the number of missed prayers is unknown, one should exercise caution (ihtiyat) until one's responsibility is cleared. The same applies to fasting: it must be made up if it was missed due to a legitimate excuse or intentionally, and caution should be exercised regarding the number if it is unknown.