What is a proper time for Qaza Namaz?

When a person misses a prayer, there could be many reasons behind it.

1. Forgetfulness: If the person forgets about the prayer.
2. Sleep: He misses prayer as he was asleep
3. Willingly: If he willingly passed time knowing its time for prayer and still not prayed and missed it. (all other reasons except 1,2 mentioned above.)

Prophet Mohammed Peace be upon him said : If a person oversleeps a salah or forgets about the salah then he should make up for it as soon as he remembers about it, as there is no expiation other than that.

1. If you forget about praying salah, you should pray as soon as you remember about it.
2. If you oversleep and miss the prayer you should pray as soon as you wake up and realize you’ve missed it.
3. If you missed a salah because of a reason which is other than the 2 mentioned above, then you can’t make it up for the salah.
   Once the time of Salah ends you can’t pray. You’ve missed it and you should ask Allah for forgiveness.