I found my lost/stolen passport
What should I do if I find a passport that I had reported lost or 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 Embassy of Ireland:
Embassy of Ireland, Suite 1105, 130 Albert St., Ottawa, ON, K1P 5G4