The IRS mails the federal tax refund check to the address entered on the tax return.
Go to this IRS website for information on reporting a lost refund check - https://www.irs.gov/faqs/irs-procedures/refund-inquiries/refund-inquiries-0
To contact the IRS from a foreign location, go to this IRS website for information - https://www.irs.gov/help/contact-my-local-office-internationally
