He pilfered some money and does not know how much, and he cannot repay it. What should he do?

No File Exists
Check below answers in case you are looking for other related questions:
Used to Take Things From Work; What Now After Repentance?
He was given more money than he was entitled to

No File Exists
Related Answers:
Partner took money from the company without his partner’s knowledge
He took some money by force from a man and he wants to repent
Acceptance of repentance
Used to Take Things From Work; What Now After Repentance?
He was given more money than he was entitled to

Recommended answers for you:
It is permissible to sleep on one’s left side
Signs of the Hour
Are the five daily prayers mentioned in the Qur'aan?
Is man’s fate pre-destined or does he have freedom of will?
The virtue of patience