For what reasons do prayers go unanswered?
Prayers never go unanswered. In fact they are answered immediately.
BG 4.12 - Acting desirous of success, those who worship the deities (deva/raksha/preta/pitru) here in this human world, the success happens quickly from those actions
BG 7.22 - Filled with that faith, that person engages in worshipping that form, and gets those very desired results as they are dispensed by Me alone.
If a devotee claims that his prayers were unanswered ...
The prayers are answered with exactly same sincerity & way, with which the prayers are offered.
BG 4.11 - The way they approach Me (direct or via deity), exactly in same way I serve them; O Partha human beings follow My path in every way.
Hence, if a person prays: "I want to be very rich.", then the result of that prayer will be immediately returned with the next thought in their mind. e.g. "I will purchase xyz." "I will travel at abc." ...
- If person prays in imagination, then gets results in imagination too like above
- If person brings the worship for money in conscience, then the prayer
will result in planning.
- If the person brings the worship in action, then the prayer will
result in hard work in a direction.
- If the person brings the worship in perseverance, then the prayer may
result in actual wealth as well
Important to note that, prayers are not limited to hands folded with eyes closed. There are various way of worshipping/praying certain aspect (deity). They are listed scattered in Gita (e.g. 4.25-4.30).
One may think,
Why sometimes, even after giving enough of efforts certain goals are not achieved?
Because the earlier prayers are in work! If a person has in early life or birth has prayed to evil traits even more intensely, then they would nullify the person's lighter prayers in present time.
Practising evil traits is as good as praying evil traits.