Allah said:
وَقَالَ الَّذِينَ اتَّبَعُواْ لَوْ أَنَّ لَنَا كَرَّةً فَنَتَبَرَّأَ مِنْهُمْ كَمَا تَبَرَّوُواْ مِنَّا
...
And those who followed will say: "If only we had one more chance to return (to the worldly life), we would disown (declare ourselves as innocent from) them as they have disowned (declared themselves as innocent from) us."
This Ayah means:
`If we only had a chance to go back to the life so that we could disown them (their idols, leaders, etc.) shun their worship, ignore them and worship Allah Alone instead.'
But they utter a lie in this regard, because if they were given the chance to go back, they would only return to what they were prohibited from doing, just as Allah said.
This is why Allah said:
...
كَذَلِكَ يُرِيهِمُ اللّهُ أَعْمَالَهُمْ حَسَرَاتٍ عَلَيْهِمْ
...
Thus Allah will show them their deeds as regrets for them.
meaning, their works will vanish and disappear.
Similarly, Allah said:
وَقَدِمْنَأ إِلَى مَا عَمِلُواْ مِنْ عَمَلٍ فَجَعَلْنَاهُ هَبَأءً مَّنثُوراً
And We shall turn to whatever deeds they (disbelievers, polytheists, sinners) did, and We shall make such deeds as scattered floating particles of dust. (25:23)
Allah also said:
مَّثَلُ الَّذِينَ كَفَرُواْ بِرَبِّهِمْ أَعْمَالُهُمْ كَرَمَادٍ اشْتَدَّتْ بِهِ الرِّيحُ فِي يَوْمٍ عَاصِفٍ
The parable of those who disbelieved in their Lord is that their works are as ashes, on which the wind blows furiously on a stormy day. (14:18)
and:
وَالَّذِينَ كَفَرُواْ أَعْمَـلُهُمْ كَسَرَابٍ بِقِيعَةٍ يَحْسَبُهُ الظَّمْأنُ مَأءً
As for those who disbelieved, their deeds are like a mirage in a desert. The thirsty one thinks it to be water. (24:39)
This is why Allah said,
...
وَمَا هُم بِخَارِجِينَ مِنَ النَّارِ
And they will never get out of the Fire.