A:
If the reality is as you have mentioned, you should exert efforts to find them through the addresses that you got when you contracted them, and you should pay them their due rights. If you are unable to do this
you should give out the money owed to each person as Sadaqah if they are Muslims, intending the reward for them. If they are non-Muslims, you should give the money in charity to free yourself of any obligation. If they come back after that, tell them what you did. If they do not accept that, you have to give them their due rights, and you will get the reward of the Sadaqah. (Part No. 14; Page No. 41) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.