is this hadith correct?: the one who forgets quran after memrizing it,will be blind on the day of judgement. I want to know about this topic in detail & all the false ahadith on this topic also.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The wording of the Prophetic narration which you referred to does not exist in the resource books of Sunnah. However, some Dha’eef narrations (i.e. inauthentic) have been reported about forgetting the Quran after having memorized it, like the narration which reads:  “The sins of my nation were exposed to me, and I did not see any graver sin than a man forgetting a chapter or verse after having memorized it.” [At-Tirmithi and Abu Daawood] There is another Dha’eef narration as well which reads: “Whoever memorizes the Quran and forgets it, will meet Allaah on the Day of Judgment mutilated.” [Ahmad]

Undoubtedly, forgetting the Quran after having memorized it is something dispraised because this is a great blessing which one has neglected. It is not befitting for a person whom Allaah has blessed with the favour of memorizing His Book to neglect this bounty until he loses it. It is for this reason that some scholars are of the view that forgetting the Quran (after having memorized it) is a grave major sin.

For more benefit on the saying of Allaah (which means): {[Allaah] will say, “Thus did Our signs come to you, and you forgot [i.e. disregarded] them; and thus will you this Day be forgotten.”}[Quran 20:126], please refer to Fatwa 81788.  

Allaah Knows best.