What do I do if I find a passport I'd reported lost/stolen?
Never travel on your passport if it has been reported lost or stolen. You run the risk of being stopped at border crossings, as Interpol keeps a record of all reports of lost or stolen passports.
You should return the passport to the Passport Office Customer Care:
Embassy of Ireland
2234 Massachusetts Ave NW,
Washington DC 20008
Tel. + 1-202-462-3939