https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment
Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return.
After you print, sign and mail your amended return—1040X— to the IRS wait about 3 weeks and then you can begin checking on it at the IRS website. Be aware that it can take at least 3-4 months for an amended return to be fully processed (or sometimes even longer.)
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1