Asalam aleikum I am 13years old and I need some help I have a question if someone dies and they have not memorised the whole Quran is it a sin ? And what if they die and they don't know any surats from the quran?
Walaykomasalam, 1) No, if a Muslim dies having not memorised the WHOLE Quran, it is not considered a sin. However it is encouraged to memorise at least parts of the Quran as it brings great rewards in this world and the Afterlife In Shaa Allah:
Ibn 'Amr reported that the Prophet (Sallallahu Alaihi wasallam) said: "It will be said to the companion of the Qur'aan after he has entered Paradise, 'Recite, and rise!' For every verse he recites he will rise one level (in Paradise), until he recites the last verse with him (i.e., in his memory)." (Aboo Dawood)
This Hadith mentions the merit of those who memorize part or all of the Qur’an. Some scholars, in explaining this Hadith, have mentioned that the number of ranks (levels) in Paradise is equal to the number of ayahs (verses) in the Qur’an, and that a believer will rise one rank for each ayah (verse) that he or she memorizes. Obviously, the one who memorised the whole Qur'an will stop at the last verse of the Quran meaning they will be of those among the highest ranks of paradise.
2)For your second question, we have to remember that in order to pray our 5 prayers, we need to memorise atleast some Surahs of the Quran, otherwise we wouldn't be able to pray. And we need to pray in order to go to Heaven:
"What led you into Hell-Fire? They will say; 'We were not of those who prayed;' (The Noble Quran, 74:42-43)"
So in order to pray we need to memorise some Surahs In Shaa Allah
I hope this helped!
May Allah SWT guide you :)