If you have tried all of the options below to get your prior year's AGI, and are still coming up empty handed, you can run through your tax return and select file by mail.
You will need to get the return in the mail today. Many post offices are open later to accommodate this, but you will need to contact them directly to find their hours.
https://ttlc.intuit.com/replies/3301618
https://ttlc.intuit.com/replies/3401713