Did the contractor fill out a form with an emergency contact? If so, you could try to contact them as a last resort. Typically, if you are holding personal property for someone and they never claim it, you have to give them 30 days notice to come and get the property. Notice must be by mail, as you have done. If they do not claim the property 60 days after the notice, then you could donate the property to charity if it worth less than $100. If it is worth more than $100, call the local police agency and drop the items off as unclaimed property.