The word(s) "lost" appears 36 time(s) in 34 verse(s) in Quran in Saheeh International translation.

(1) And how many a prophet [fought and] with him fought many religious scholars. But they never lost assurance due to what afflicted them in the cause of Allah, nor did they weaken or submit. And Allah loves the steadfast.

(2) And Allah had certainly fulfilled His promise to you when you were killing the enemy by His permission until [the time] when you lost courage and fell to disputing about the order [given by the Prophet] and disobeyed after He had shown you that which you love. Among you are some who desire this world, and among you are some who desire the Hereafter. Then he turned you back from them [defeated] that He might test you. And He has already forgiven you, and Allah is the possessor of bounty for the believers.

(3) They receive good tidings of favor from Allah and bounty and [of the fact] that Allah does not allow the reward of believers to be lost -

(4) And their Lord responded to them, "Never will I allow to be lost the work of [any] worker among you, whether male or female; you are of one another. So those who emigrated or were evicted from their homes or were harmed in My cause or fought or were killed - I will surely remove from them their misdeeds, and I will surely admit them to gardens beneath which rivers flow as reward from Allah, and Allah has with Him the best reward."

(5) See how they will lie about themselves. And lost from them will be what they used to invent.

(6) Those will have lost who deny the meeting with Allah, until when the Hour [of resurrection] comes upon them unexpectedly, they will say, "Oh, [how great is] our regret over what we neglected concerning it," while they bear their burdens on their backs. Unquestionably, evil is that which they bear.

(7) [It will be said to them], "And you have certainly come to Us alone as We created you the first time, and you have left whatever We bestowed upon you behind you. And We do not see with you your 'intercessors' which you claimed that they were among you associates [of Allah]. It has [all] been severed between you, and lost from you is what you used to claim."

(8) Those will have lost who killed their children in foolishness without knowledge and prohibited what Allah had provided for them, inventing untruth about Allah. They have gone astray and were not [rightly] guided.

(9) Do they await except its result? The Day its result comes those who had ignored it before will say, "The messengers of our Lord had come with the truth, so are there [now] any intercessors to intercede for us or could we be sent back to do other than we used to do?" They will have lost themselves, and lost from them is what they used to invent.

(10) But those who hold fast to the Book and establish prayer - indeed, We will not allow to be lost the reward of the reformers.