What should I do about damaging a hotel curtain in another country over two years ago, given my regret for not informing anyone, my lack of knowledge about the hotel's name or room number, and is it permissible for me to ask my father about this?

You are considered a trustworthy tenant, and you are not liable unless you exceeded your bounds or were negligent in damaging the curtain. Otherwise, you are responsible for guaranteeing it. The guarantee must be paid to the hotel owner unless he forgives you, as intentional and unintentional damage to people's property are both the same. If you can reach the hotel owner, you are obliged to pay him his due. If you cannot, it is permissible to give the value of what you damaged as charity on his behalf.