Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Whoever sleeps through or has forgotten to pray a certain prayer should pray it when he wakes up or remembers the prayer.
In his famous work, Fiqh As-Sunnah, Sheikh Sayyid Sabiq, elaborates on the subject as follows:
Whoever sleeps through or has forgotten to pray a certain prayer should pray it when he wakes up or remembers the prayer.
Abu Qatadah (may Allah be pleased with him) related that sleeping through the prayer time was mentioned to the Prophet (peace be upon him) and he said, “There is no negligence in sleep, but negligence occurs while one is awake. If one of you forgets a prayer or sleeps through its time, then he should pray it when he remembers it.” (Reported by an-Nasa’i and at-Tirmizhi who said it is sahih.)
Anas (may Allah be pleased with him) related that the Prophet (peace be upon him) said, “Whoever forgets a prayer should pray it when he remembers it, and there is no expiation for it save that.” (Al-Bukhari and Muslim)
`Imran ibn al-Husain (may Allah be pleased with him) reported, “We went with the Messenger of Allah during the night. When the last portion of the night came, we became tired and fell asleep. We did not wake until we felt the heat of the sun. Some of us tried hurriedly to purify ourselves. The Prophet ordered us to be calm. Then we rode on until the sun had risen and we made ablution. He ordered Bilal to make the call to prayer, and then prayed two rak`ah before the (obligatory) morning prayer. Then we stood and prayed. We said, ‘O Messenger of Allah, should we not repeat it tomorrow in its proper time?’ He said, ‘Would your Lord the Most High forbid you from interest and accept it from you?”‘ (Ahmad and others)
For more, see these fatwas:
What to Do If You Miss Rakah in Your Prayer
Joined Friday Prayer in the Last Tashahhud: Did I Miss the Prayer?
What Should You Do If You Miss First Tashahhud?
When to Offer Missed Isha Prayer
Almighty Allah knows best.