With regard to missing prayers it has two cases:

1 – If prayer is missed unintentionally, for a legitimate shar’i excuse, such as forgetting or sleeping, although a Muslim is basically very keen to perform the prayer on time, in this case, he or she is excused but he has to make it when he or she remembers it. The evidence for that is the hadith narrated in Muslim which tells how the Prophet (peace and blessings be upon him) and his companions slept and missed Fajr prayer, and the companions began to ask one another, “What is the expiation (kafarah) for what we have done by neglecting the prayer?” The Messenger of Allah (peace and blessings be upon him) said, “Sleeping does not mean that you are neglecting the prayer. Rather neglecting the prayer means not praying one prayer until the time for the next prayer comes. Whoever does that let him pray when he remembers it.” 

This does not mean that a person should sleep deliberately when a prayer is due, until he misses it, then maintain sleep as an excuse, or neglect a means that would help him to do the prayer, and then take that as an excuse. Rather he must make use of all the means he can, as the Messenger (peace and blessings be upon him) did in this case, when he appointed one person to stay awake and wake them up to pray, but that person was overcome by drowsiness, so he did not wake them up. This is the case in which a person may be excused.

2 – When a person misses a prayer deliberately. This is a major sin, and it is so serious that some of the scholars stated that the one who does this is a kafir (non-Muslim). The one who does this has to repent sincerely, according to scholarly consensus. With regard to making up the prayer, there was a difference of opinion among the scholars as to whether or not it would be accepted from him if he makes it up afterwards. Most of the scholars said that he should make it up and that his prayer is valid, although he is a sinner (i.e. if he does not repent), as Shaykh Ibn ‘Uthyameen quoted from them in ash-Sharh al-Mumti’, 2/89.

Thus, you are required to perform the missed prayer when you remember it and it is not permissible to delay it. It should be noted that you are required to observe the order of prayers, such as to perform the missed `Isha’ before the Fajr of the next day.

May Allah guide all of us to what pleases Him!