Is it permissible to use a watch that was left as a trust (amanah) and its owner did not come to collect it at the appointed time?

You must be patient until the owner of the watch comes and gives you your right. If patience becomes difficult for you, sell it in the market for the highest price, then take your right and keep the remainder for its owner. If its owner comes at any time, give him his money. If a long time passes and you are unable to find its owner or send his right to him, then give it as charity to the poor on his behalf.