Is money earned from selling a car that was seized during wartime permissible (halal), and how can it be returned to its unknown owner?

If you were compelled to travel by car, then you seized it and sold it, this is consuming people's wealth unlawfully and is forbidden شرعًا (religiously). You must repent to Allah, and if the car was not used before being taken, then you must return its equivalent to its owner. However, if it was used or new and it is now impossible to find its equivalent, then you must return its value on the day it was seized. If you despair of reaching its owner or their heirs, then give that value as charity on their behalf.