What is the ruling regarding missed prayers for one who did not pray but then repented and became regular in their prayers?

Remember God's blessing upon you by returning you to Islam, and be diligent in performing prayers on time. Increase your voluntary prayers (nawafil) to compensate for any missed obligatory prayers (fara'id), as the Prophet, peace and blessings be upon him, said: "Indeed, the first thing a servant will be called to account for on the Day of Resurrection from his deeds is his prayer. If it is sound, he will have succeeded and prospered. But if it is corrupt, he will have failed and lost. If there is any deficiency in his obligatory prayers, the Lord, the Mighty and Majestic, will say: 'Look, does My servant have any voluntary prayers (tatawwu') with which to complete what was deficient in his obligatory prayers?' Then all his other deeds will be dealt with in the same way."