If a religious, generous, kind-hearted person dies unnaturally in an accident what happens to its soul? The person had done great works in his life of 46 years and on the second hand, he was a businessman and always had many worries/problems related to work and family. I didn't find the answer I require in any other question.
This is not that easy to answer: It doesn't depend on whether the death is natural or unnatural.
Gita gives a clue about this.
Soul moves to next destination
वासांसि जीर्णानि यथा विहाय नवानि गृह्णाति नरोऽपराणि। तथा शरीराणि विहाय जीर्णा न्यन्यानि संयाति नवानि देही
2.22 As after rejecting wornout clothes a man takes up other new ones, likewise after rejecting wornout bodies the embodied one unites with other new ones.
Where soul goes depends and even that is not so easy to say
यं यं वापि स्मरन्भावं त्यजत्यन्ते कलेवरम्। तं तमेवैति कौन्तेय सदा तद्भावभावितः 8.6 On whatever sphere of being the mind of a man may be intent at the time of death, thither he will go.
गहना कर्मणो गतिः 4.17: for mysterious is the law of action
ऊर्ध्वं गच्छन्ति सत्त्वस्था मध्ये तिष्ठन्ति राजसाः। जघन्यगुणवृत्तिस्था अधो गच्छन्ति तामसाः 14.18 People who conform to sattva go higher up; those who conform to rajas stay in the middle; those who conform to tamas, who conform to the actions of the lowest ality, go down.
Don't worry. If he did good karma, he will get good birth as per above Gita verses. Just do post death rituals nicely.
Hope it helps!!